A collection of musings, research and reflective thoughts on topics that spark my curiosity, interest or just simply inspire me. Any views or opinions expressed within each post are my own. I welcome all feedback and opportunities to collaborate with like-minded individuals, but please keep comments polite, courteous and respectful at all times.
Saturday, 22 November 2025
Poem: Being Well
Wednesday, 19 November 2025
Poem: Teacher to the Gods
Monday, 17 November 2025
Poem : Lighthouse - the Silent Sentinel
Saturday, 15 November 2025
Essay: Reflecting on the Legacy of James Dewey Watson (6 April 1928 – 6 November 2025) π§¬
Thursday, 13 November 2025
Poem: The Gift of Kindness...
In this world, trust is a fragile thread,
Betrayal's sting leaves heartache widespread.
Once held close, now torn apart,
Yet from the ashes, there is a fresh new start.
In the shadows of ignorance, where we once dwelled,
Lost in the depths where truth seemed repelled.
But through kindness, a beacon of light we find,
Illuminating the path to hearts intertwined.
Through the pain, we find a spark,
A flame of kindness in the dark.
No vengeance sought, no grudge to bear,
But rather, love beyond compare.
With each act, we mend and seal,
Healing wounds into joy revealed.
And in this transformation, we see,
The ripple effect for eternity.
For kindness not only heals the present hour,
But sows seeds of compassion with enduring power.
Through generations, its legacy shall endure,
A testament to love, forever pure.
Though scars may linger, wounds will mend,
The gift of kindness has no end.
For in its embrace, we find our worth,
A treasure found in every birth.
So let us cherish, let us share,
The gift of kindness, beyond compare.
For in its grace, we truly see,
The beauty of humanity.
By Adisha Kariyawasam
Wednesday, 12 November 2025
Poem: The Violinist π»
Poem: The Whisper of Hope...
For all who have loved deeply and lost dearly - may the rising sun remind you that love never fades,
it simply changes form and continues to shine
in the quiet whisper of each new dawn.
The Whisper of Hope...
In the cradle of dawn’s tender hue,
The sky awakens in shades anew.
Through parting clouds, soft light will slope,
A gentle reminder, a whisper of Hope.
Each sunrise sings though hearts may weep,
Love’s promise stirs from its quiet sleep.
No night endures, no shadow can cope,
For day returns with a whisper of Hope.
Tears may glisten, like dew reborn,
Yet they nourish dreams through every morn.
For even in sorrow, the spirit can cope,
When hearts are healed by a whisper of Hope.
So let us rise where soft rays gleam,
And hold our loved ones in each dream.
For every dawn helps hearts to cope,
Renewing life in the whisper of Hope.
Adisha Kariyawasam
12/11/2025
π€ #Hope
πΏ #Healing
π #Remembrance
π« #NewBeginnings
π #Poetry
Poem: Stay Centred...
Lately, I’ve been reflecting on how easy it is to drift away from our centre - caught between deadlines, expectations, and the constant hum of daily life. Yet, thankfully, whenever I take a mindful pause, I’m reminded that peace has always been within reach.
We each have the power to let stress wash away - through gratitude, kindness, and by remembering the good moments that uplift our spirit. Staying centred isn’t about perfection; it’s about gently returning to balance whenever life pulls us off course.
My poem, “Staying Centred” is a quiet reminder to slow down, breathe, and reconnect with who we truly are. π
Staying Centred...
Stay centred, calm, and wholly you,
no mask to wear, no act to do.
For peace begins when we allow
the heart to rest in here and now.
Let kindness flow through all you say,
and wash the restless thoughts away.
Remember joy - the gentle art
of gratitude that lifts the heart.
The storms may come, the noise may grow,
but truth within will softly show:
your light remains, serene and clear,
a beacon shining ever near.
So breathe, be still, embrace the hue
of every shade that makes you you.
For when you walk with calm and grace,
you’ll find your balance - your sacred place.
by Adisha Kariyawasam
12/11/2025
πΏ #Authenticity
π« #Balance
π #Gratitude
π #MindfulLiving
π #Poetry
Tuesday, 11 November 2025
Poem: The Train Journey
Poem: Armistice Day - Lest We Forget...
Poem: One Mindful Breath (The GREAT DREAM)
Monday, 10 November 2025
Poem: Spoken Words Can Heal Too...
Spoken Words Can Heal Too...
There are times when our words can heal in ways that medicine alone never could — with gentle strength, lasting impact, and a kindness that endures.
This poem is dedicated to all those on the front line — in healthcare, education, community service, and beyond — as a gentle reminder of the quiet power of the spoken word.
It is also dedicated to anyone who has ever been hurt by harsh words or unkindness.
May this serve as a reminder that with timely action, empathy and support, healing is always possible. π
Spoken Words Can Heal Too…
Let’s make time to talk, with gentle care,
a healing gift that hearts can share.
Each tender word, when softly spoken,
becomes medicine for a soul that’s broken.
A tender voice with good intent,
breathes life where tired hearts are spent.
It lifts the weary, stirs the whole,
like rising tides that raise each soul.
When hearts in tune begin to speak,
resonance flows — both strong and meek.
Through synchronicity, souls align,
and gentle words bring love divine.
So pause a while, and truly hear,
the hopes, the hurts, the voice so near.
In giving time, our spirits blend,
and pain begins its path to mend.
Through honest talk, through patient grace,
we find true bond, in face-to-face.
For when we speak and when we feel,
we learn — through love — that spoken words can heal too.
Adisha Kariyawasam
11 November 2025
#Empathy π€
#HealingWords π¬
#MindfulCommunication π️
#Poetry✍️
#Wellbeing π
Poem: A Sense of Joy
A Sense of Joy
I find that some days, when the world outside feels still and grey, our hearts can find warmth - not in the present moment, but in the memories that shaped who we are.
This poem is a gentle reflection on those cherished moments — the ones that remind us of love, peace, and the simple joy of just being.
A Sense of Joy
my heart drifts gently far away —
to moments wrapped in tender light,
where memory glows through quiet night.
soft echoes by the sunlit door,
the gentle hand that held my own,
the sweetest peace I’ve ever known.
a timeless spark of happiness.
The sunlight through the swaying trees,
the sea’s warm sigh, the salty breeze.
“You are enough — you’re still right here.”
For joy once lived is never gone,
it lives in us — and carries on.
Adisha Kariyawasam
10/11/2025
πΏ #MindfulMoments
π #Nostalgia
πΈ #PoetryForHealing
π #Wellbeing
Sunday, 9 November 2025
Poem: You Are Brave Enough
You Are Brave Enough...
My poem for anyone who needs this right now... ππΌ
"You Are Brave Enough..."
You are brave enough to face what comes,
strong enough to bend, not break.
Each challenge is a teacher in disguise,
each setback a chance to awake.
You can stand tall through the storm,
and still find calm within the rain.
You can stumble, pause, and try again
and still rise with purpose from the pain.
Your courage is not the roar of battle,
but the quiet whisper, “I’ll try once more.”
For every day you choose to continue
is a victory worth fighting for!
By Adisha Kariyawasam
09/11/2025
π¦ #Courage
π #PoetryForHealing
✨ #PositiveAffirmations
π± #Resilience
πΈ #Wellbeing
Essay: The Importance of Face-to-Face Learning in a GenAI Influenced World
π± The Importance of Face-to-Face Learning in a GenAI Influenced World
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| Face-to-face learning: the human connection at the heart of education. |
Author: Adisha Kariyawasam BSc , MScIT, PGCE (PCET), BCS
In an age of algorithms, automation and virtual classrooms, it’s easy to overlook the quiet power of being together. Yet face-to-face learning remains one of the most profoundly human experiences we can share – a space where intellect meets intuition and knowledge turns into wisdom.
Beyond information: the energy of presence
When people learn in the same room, something remarkable happens. It’s not just about exchanging information; it’s about sharing energy. The subtle cues – a smile, a nod, a pause of reflection – create a rhythm that’s hard to replicate through a screen.
There’s something that taps into the superhuman consciousness when we learn together – an energy that transcends words, flowing through curiosity, empathy and shared discovery. These are the moments that spark creativity, belonging and authentic growth.
Recent UK research confirms this: students express greater satisfaction and perceive higher learning quality when taught face-to-face compared with fully online delivery (McGill et al., 2023). The social energy of physical presence enhances attentiveness, motivation and a shared sense of purpose.
Learning as connection, not transaction
Digital tools and AI have revolutionised access to education – but true education has never been purely transactional; it is relational. It flourishes in trust, dialogue and mutual respect.
Digital tools and AI have revolutionised access to education – but true education has never been purely transactional; it is relational. It flourishes in trust, dialogue and mutual respect.
At BPP University, these values are embedded in how we teach and lead:
1. Everybody Matters – valuing each individual and recognising every contribution.
2. Trust and Respect – behaving with honesty, accountability and professionalism.
3. Stronger Together – collaborating across teams and disciplines to achieve shared goals.
4. Embrace Change – innovating and adapting confidently in a dynamic world.
5. Student, Learner and Client Centric – listening, empathising and responding to those we serve.
These are not slogans but lived values that shape the classroom experience.
Face-to-face learning embodies these principles in action: it cultivates social presence – the sense of “being with” others – which research consistently links to stronger engagement, confidence and learning outcomes (O’Brien et al., 2023).
Students in UK higher education still overwhelmingly prefer in-person teaching (HEPI, 2021), viewing it as central to genuine human connection and mutual growth.
Technology as an ally, not a substitute
AI can enhance how we learn – offering flexibility, feedback and accessibility – but it cannot replace the spark of human connection. The challenge for educators today is not to choose between human and machine, but to weave them together mindfully.
Technology should serve humanity, not dilute it. The future of education lies in balance – using innovation to amplify, not replace, the power of presence. The UK Parliamentary Office of Science and Technology (2023) highlights that while digital learning can widen access, sustained in-person interaction remains vital for deep engagement and equitable participation.
Critical thinking, evaluation and reflective practice
In addition to connection and collaboration, face-to-face environments play a vital role in cultivating critical thinking and evaluative judgement. Facilitated discussions allow learners to question, debate and refine ideas in real time – a process that stimulates analytical depth and intellectual confidence (Trowler, 2023).
Handwritten note-taking, often undervalued in the digital age, remains a powerful cognitive tool, supporting memory retention and conceptual understanding (Mueller and Oppenheimer, 2014). Encouraging students to digitise and share these notes or reflections through discussion forums extends the dialogue beyond the classroom, creating a living record of collective learning.
This integration of analogue reflection and digital sharing bridges the best of both worlds – supporting metacognition while reinforcing the social and collaborative nature of learning (Jisc, 2023).
Where minds meet, transformation begins
Face-to-face learning is not merely about proximity; it’s about presence. It reminds us that education is as much about becoming as it is about knowing – a shared act of discovery that strengthens both mind and heart. Other important considerations follow...
Social–emotional development
Why it matters: Social–emotional learning (SEL) fosters empathy, resilience and collaboration – essential qualities for both personal and professional growth.
Face-to-face advantage: In-person environments enhance emotional attunement through real-time cues, enabling learners to practise empathy and communication.
Evidence: Studies in UK higher education show that social-emotional skill development correlates strongly with classroom presence and belonging (TASO, 2023). Reduced physical interaction during online periods weakened students’ sense of community and wellbeing (Behavioural Insights Team, 2022).
Example: In small seminar settings, eye contact, dialogue and immediacy build trust and encourage risk-taking – the conditions for authentic learning (O’Brien et al., 2023).
Employability skills
Networking and communication: Face-to-face learning provides spontaneous opportunities to connect, network and build professional relationships.
Practical and teamwork skills: In-person collaboration develops real-world competencies – teamwork, adaptability and interpersonal fluency – that employers value highly.
Evidence: Employer and student surveys indicate that graduates from blended or in-person programmes report stronger professional confidence and communication skills than their online-only peers (Jisc, 2023).
Face-to-face experiences also allow learners to engage with mentors, industry guests and live projects – experiences that are central to employability (HEPI, 2021).
Intercultural competence
Global citizenship: Exposure to diverse peers in physical classrooms enhances intercultural sensitivity and global awareness.
Embodied understanding: Real-world dialogue allows cultural nuances – tone, gesture and empathy – to enrich understanding beyond the textual.
Evidence: While virtual international initiatives such as Collaborative Online International Learning (COIL) promote global interaction, UK evidence suggests that in-person encounters remain uniquely effective in improving engagement and academic performance (University of Bath, 2023).
Practical design take-aways
1. Protect presence: Reserve face-to-face sessions for activities requiring co-presence – debate, teamwork, presentations, simulations.
2. Blend with intent: Use digital tools for flexibility and self-paced learning; use in-person time for dialogue and application.
3. Engineer social presence: Promote interaction through name-learning, peer mentoring and collaborative artefacts.
4. Map to employability: Embed teamwork, communication and leadership skills within live classroom tasks.
5. Design for intercultural growth: Integrate international perspectives and structured reflection in both physical and digital spaces.
References
Behavioural Insights Team (2022) Digital learning. Available at: https://www.bi.team/articles/digital-learning/ (Accessed: 8 November 2025).
HEPI (2021) The vast majority of students want in-person learning, not more online classes. Available at: https://www.hepi.ac.uk/2021/07/15/the-vast-majority-of-students-want-in-person-learning-not-more-online-classes/ (Accessed: 8 November 2025).
Jisc (2023) Does online learning deter university applicants? Available at: https://www.jisc.ac.uk/blog/does-online-learning-deter-university-applicants/ (Accessed: 8 November 2025).
McGill, L. et al. (2023) ‘Student preferences over module design: in-person lectures versus online lectures’, Discover Education. Available at: https://link.springer.com/article/10.1007/s44217-024-00270-z (Accessed: 8 November 2025).
Mueller, P.A. and Oppenheimer, D.M. (2014) ‘The pen is mightier than the keyboard: Advantages of longhand over laptop note taking’, Psychological Science, 25(6), pp. 1159–1168.
Murray, K. (2025) ‘The third space professional: cultivating authentic learning experiences for students in higher education’, Journal of Learning Development in Higher Education. Available at: https://journal.aldinhe.ac.uk/index.php/jldhe/article/view/1223 (Accessed: 9 November 2025).
O’Brien, A. et al. (2023) ‘Face-to-face vs. blended learning in higher education: a quantitative study’, International Journal of Educational Technology in Higher Education. Available at: https://research.edgehill.ac.uk/en/publications/face-to-face-vs-blended-learning-in-higher-education-a-quantitati (Accessed: 8 November 2025).
Parliamentary Office of Science and Technology (2023) Digital education and learning technologies. Available at: https://post.parliament.uk/research-briefings/post-pn-0639/ (Accessed: 8 November 2025).
Quinlan, K. M., Sellei, G. and Fiorucci, W. (2024) ‘Educationally authentic assessment: reframing authentic assessment in relation to students’ meaningful engagement’, Teaching in Higher Education, 30(3), pp. 717–734. Available at: https://kar.kent.ac.uk/107151/ (Accessed: 9 November 2025).
TASO (2023) Online teaching and learning in the time of COVID-19: rapid evidence review. Available at: https://cdn.taso.org.uk/wp-content/uploads/2023-03-22_Evidence-review_Online-teaching-and-learning-in-COVID-19_TASO.pdf (Accessed: 8 November 2025).
Times Higher Education and Adobe (2023) Authentic Assessment in Higher Education and the Role of Digital Creative Technologies. Available at: https://www.adobe.com/content/dam/cc/uk/education/higher-education/digital-edge-award-2024/Authentic-Assessment-Higher-Education-Role-Digital-Technologies-2023.pdf (Accessed: 9 November 2025).
Trowler, V. (2023) Student engagement and higher education learning communities: Critical thinking in practice. York: Advance HE.
University of Bath (2023) Study shows university students who attend seminars in person enjoy better exam results. Available at: https://www.bath.ac.uk/announcements/study-shows-university-students-who-attend-seminars-in-person-enjoy-better-exam-results/ (Accessed: 9 November 2025).
University of Edinburgh/Napier-repository (2023) Authentic learning in higher education environments: teacher insight into student experience. Available at: https://napier-repository.worktribe.com/output/3110589/authentic-learning-in-higher-education-environments-teacher-insight-into-student-experience-a-reflection-of-process-and-purpose-stage-1-with-focus-on-edinburgh-case (Accessed: 9 November 2025).
Appendix 1: Glossary of Abbreviations and Key Terms
AI - Artificial Intelligence : The simulation of human intelligence by computer systems that can perform tasks such as reasoning, learning and decision-making. Artificial Intelligence encompasses a range of subfields, including machine learning and Generative AI (GenAI) — systems capable of creating new content such as text, images, code or music based on patterns in existing data.
Inference refers to the process by which AI models apply learned patterns to make predictions or generate outputs from new, unseen data. In higher education, AI and GenAI are increasingly used to support adaptive learning, data analysis and creative exploration, while raising important questions of ethics, originality and academic integrity.
Authentic Assessment : An approach to evaluating learning that focuses on applying knowledge, skills and values to realistic, complex tasks. Authentic assessments mirror professional practice and require students to demonstrate understanding through problem-solving, reflection and performance in real-world or simulated contexts. Contemporary UK research highlights how authentic assessment enhances engagement, employability and digital literacy (Quinlan, Sellei and Fiorucci, 2024; Times Higher Education & Adobe, 2023).
Authentic Learning : A pedagogical approach linking academic concepts to real-world contexts, encouraging learners to apply knowledge through meaningful, practical and collaborative experiences. Authentic learning promotes critical thinking, reflection and problem-solving by connecting theory to professional practice (Murray, 2025; University of Edinburgh/Napier, 2023).
BPP University Values : BPP’s culture is built around five core values that guide behaviour, decision-making and how staff support learners, students and clients:
1. Everybody Matters – We value people over hierarchy and recognise the contribution of every colleague and learner.
2. Trust and Respect – We act with honesty, accountability and professionalism, building relationships based on mutual respect.
3. Stronger Together – We collaborate across teams and disciplines to remove silos and achieve shared goals.
4. Embrace Change – We challenge the norm, innovate and stay agile in a changing educational landscape.
5. Student, Learner and Client Centric – We listen, empathise and respond to the needs of those we serve, aiming to delight and create impact.
Blended Learning : A method combining digital technologies with traditional classroom teaching to create flexible and interactive learning experiences.
COIL - Collaborative Online International Learning : A structured model linking students and educators across borders through online projects that foster intercultural competence.
Digital Learning : Learning supported or delivered through digital technologies such as virtual classrooms, multimedia platforms and AI-enhanced tools.
Employability Skills : Transferable abilities – teamwork, communication, adaptability and problem-solving – that prepare learners for success in professional contexts.
Face-to-Face Learning (F2F) : Education delivered in person, allowing immediate feedback, shared presence and non-verbal interaction.
HEPI - Higher Education Policy Institute (UK) : A think tank analysing UK higher-education policy and student experience.
Hybrid Learning : A delivery model combining synchronous (live) and asynchronous (self-paced) participation, integrating online and physical learning spaces.
Jisc - Joint Information Systems Committee : A UK organisation supporting digital transformation and innovation in education and research.
Learning Presence : The degree to which learners project themselves cognitively, socially and emotionally within a learning community.
Parliamentary Office of Science and Technology (POST) : An independent UK body providing Parliament with impartial research on science, technology and digital education policy.
PRME - Principles for Responsible Management Education : A UN-supported initiative promoting sustainability and ethical leadership within management and business education.
SEL - Social and Emotional Learning : An educational process that develops self-awareness, empathy and interpersonal skills essential for wellbeing and collaboration.
Social Presence : The ability of learners to project themselves authentically in a learning environment, fostering trust, dialogue and community.
TASO - Transforming Access and Student Outcomes in Higher Education : A UK centre promoting equity and evidence-informed practice in widening participation and student success.
VLE Virtual Learning Environment : A digital platform (e.g. Moodle, Blackboard or Canvas) used to host course materials, support communication and track progress.
Appendix 2: Summary of Key UK Evidence Sources (2021–2025)
Behavioural Insights Team (2022)
An independent UK-based organisation applying behavioural science to improve public policy and services. Their Digital Learning review examined how online delivery affects engagement, motivation, and learner outcomes, highlighting the ongoing importance of human connection in education.
https://www.bi.team/articles/digital-learning/
HEPI – Higher Education Policy Institute (2021)
The UK’s leading higher education think tank, providing data-driven insights on student experience and university policy. A 2021 report revealed that the vast majority of UK students still prefer in-person learning, citing the value of live discussion, social belonging, and community.
Jisc (2023)
A UK non-profit organisation supporting digital transformation across education and research. Their 2023 report Does Online Learning Deter University Applicants? found that students continue to view in-person interaction as central to the university experience and professional development.
https://www.jisc.ac.uk/blog/does-online-learning-deter-university-applicants/
McGill et al. (2023) – Discover Education Study
A UK-based academic study exploring student preferences for in-person versus online lectures. It confirmed that physical presence supports concentration, engagement, and comprehension, particularly in discussion-led disciplines.
https://link.springer.com/article/10.1007/s44217-024-00270-z
O’Brien et al. (2023) – Edge Hill University Research
This UK quantitative study compared face-to-face and blended learning outcomes across disciplines. Findings emphasised that hybrid approaches can enhance flexibility, but face-to-face engagement remains critical for collaboration, confidence, and deeper learning.
Parliamentary Office of Science and Technology (2023)
A research office within the UK Parliament producing impartial briefings on science and education policy. The Digital Education and Learning Technologies report stresses that while technology improves access, meaningful learning still depends on interpersonal interaction and inclusive teaching design.
https://post.parliament.uk/research-briefings/post-pn-0639/
TASO – Transforming Access and Student Outcomes (2023)
A UK centre for evidence-based practice in higher education, focused on widening participation and equity. Its rapid review of Online Teaching and Learning During COVID-19 found that while online tools offer flexibility, they cannot fully replace the sense of belonging and social support cultivated in classrooms.
University of Bath (2023)
Study shows university students who attend seminars in person enjoy better exam results
A University of Bath research announcement highlighting empirical evidence that students who physically attend seminars and workshops perform significantly better in examinations than those relying solely on recorded or remote participation. The study reinforces the cognitive and motivational advantages of in-person learning — notably higher engagement, sustained attention and improved recall — underscoring the role of presence, discussion and feedback in academic success.
https://www.bath.ac.uk/announcements/study-shows-university-students-who-attend-seminars-in-person-enjoy-better-exam-results/ (Accessed: 9 November 2025)
Tuesday, 4 November 2025
Essay: Cation Binding Sites in Chicken Annexin V – Literature Review
Cation Binding Sites in Chicken Liver Annexin V [CLAV]
Author: Adisha Kariyawasam BSc Molecular Biophysics, MScIT, PGCE (PCET), BCS
Originally written 1992–1993, BSc (Hons) Molecular Biophysics, University of Leeds
Republished and expanded 2025
Preface (2025 Edition)
This literature review was written in 1992–1993, prior to embarking on my final-year dissertation project, during the concluding phase of my BSc (Hons) Molecular Biophysics degree at the University of Leeds. It formed the preparatory groundwork for experimental work undertaken later that academic year within the Department of Biophysics.
At the time, the field of calcium-binding proteins was rapidly expanding. Researchers were discovering how divalent cations such as Ca²⁺ acted not merely as cofactors but as dynamic regulators of cellular communication, membrane fusion, and blood coagulation. This essay reflects the early stages of structural calcium biology that has since evolved into a major interdisciplinary research area, bridging molecular biophysics, physiology, and medical science.
Cation Binding Sites in Chicken Liver Annexin V [CLAV]
Introduction
Calcium ions (Ca²⁺) are essential to life, serving structural, catalytic, and regulatory functions. They stabilise extracellular matrices, act as intracellular messengers, and modulate enzyme activity. In vertebrates, cytosolic Ca²⁺ concentrations are tightly controlled at approximately 10⁻⁷ M, with transient spikes conveying signalling information.
Among the most intriguing Ca²⁺-binding proteins are the Annexins, a family of calcium-dependent phospholipid-binding proteins that play roles in membrane fusion, inflammation control, and anticoagulation.
Calcium Binding in General and in Proteins
In many biomolecules, Ca²⁺ is coordinated by oxygen atoms arranged in a pentagonal bipyramidal geometry with average Ca–O distances of 2.4 Γ . Slight displacements of ligands can yield an octahedral coordination, accommodating other divalent cations such as Mg²⁺.
Most calcium-binding proteins exhibit a coordination number of seven, using oxygen atoms from carboxylate side chains (Asp, Glu), carbonyl groups, and water molecules. These binding geometries define the selectivity and flexibility of calcium interactions in biological systems.
Classes of Calcium-Binding Proteins
Three main classes of Ca²⁺-binding proteins can be distinguished:
-
Extracellular enzymes and structural proteins, where calcium enhances thermal stability or protects against proteolysis.
-
Intracellular regulatory proteins, which bind Ca²⁺ reversibly to modulate enzyme activity. These typically feature repeating motifs such as the EF-hand, a helix–loop–helix structure found in calmodulin, troponin C, and parvalbumin.
-
Annexins, a unique family of amphipathic proteins that bind phospholipids in a calcium-dependent manner but lack the EF-hand motif.
The EF-Hand Motif
The EF-hand, named for its E and F helices, consists of a 12-residue loop flanked by Ξ±-helices. Side-chain oxygens from residues such as Asp, Ser, and Thr coordinate a single Ca²⁺ ion, while backbone carbonyls contribute additional ligands. The motif usually occurs in pairs related by a pseudo-twofold symmetry axis, forming cooperative Ca²⁺-binding sites.
Although Annexins lack this structure, understanding the EF-hand provides a comparative framework for interpreting their calcium-binding behaviour.
Annexins: Structure and Characteristics
Annexins are acidic, calcium-dependent proteins that bind to negatively charged phospholipid membranes. They share a conserved structural core composed of four homologous domains, each containing five Ξ±-helices (A–E).
Their canonical calcium-binding motif is distinct from the EF-hand, typically represented as:
–K–G–X–G–T–(38 residues)–D/E–,
where X can be any amino acid.
Binding occurs predominantly at loop regions between helices, particularly within domains I, II, and IV. Upon calcium binding, the protein undergoes conformational changes that facilitate membrane association.
Chicken Annexin V
The crystal structure of chicken Annexin V (also known as anchorin CII) was solved to 2.54 Γ resolution in 1992. The protein, with a molecular weight of 36 kDa and 320 amino acids, exhibits a bowl-shaped configuration with its convex surface exposed to solvent and the concave surface interacting with membranes.
Domains I & IV and II & III form tightly associated pairs, yet can slide relative to one another in the plane of the membrane. Both the N- and C-termini reside within domain IV. The overall molecular dimensions are approximately 64 Γ × 40 Γ .
Only the loop regions of domains I, II, and IV contain confirmed Ca²⁺-binding sites, primarily coordinated by carboxylate side chains from Asp and Glu residues.
Predicted Lanthanum Binding Sites
In 1990, Robert Huber and colleagues determined the structure of human Annexin V, revealing two additional cation-binding sites when crystals were soaked in lanthanum nitrate. Surprisingly, the crystals initially cracked but reformed within half an hour, suggesting reversible structural accommodation.
Given the high sequence homology (≈ 78 %) between human and chicken Annexin V, it was reasonable to predict analogous lanthanum-binding sites in the avian protein, located between helices A–B and C–D of domain I.
Unlike the canonical calcium-binding sites, these lanthanum positions lacked full coordination shielding, suggesting partial hydration and weaker binding affinity. Nonetheless, they hinted at potential regulatory or allosteric roles for non-physiological cations in crystal packing and structural flexibility.
Proposed Experimental Approach (1993 Project Plan)
The planned experimental work involved soaking trigonal crystals of chicken Annexin V in lanthanum nitrate and collecting X-ray diffraction data using a Xentronics Area Detector. Structural differences would be determined by calculating difference electron-density maps (Fβ – Fβ), phased with the native structure.
Each crystal measured only around 0.17 mm in width and had to be graded for optical clarity and absence of twinning before mounting. The manipulation of these fragile crystals demanded exceptional dexterity; in many cases, they were transferred into narrow 0.2mm quartz capillary tubes using a single human eyelash affixed to a matchstick - a traditional crystallographer’s tool of remarkable delicacy.
The resulting diffraction data were expected to reveal lanthanum-binding positions and any local conformational changes. It was hypothesised that crystal cracking and reformation would not permanently disrupt the protein’s tertiary architecture.
Computational Visualisation of 3D Structures (1992–1993 Context)
During the early 1990s, the interpretation of macromolecular structures relied heavily on stereoscopic computer graphics workstations. At the University of Leeds and other leading biophysics centres, crystallographers used Silicon Graphics (SGI) Indigo and Personal IRIS systems, as well as Evans & Sutherland PS300 vector graphics terminals, to visualise and manipulate protein models derived from X-ray diffraction data.
Molecular coordinates, refined using programs such as PROLSQ and X-PLOR, were rendered as wireframe or ribbon representations that could be viewed stereoscopically using polarised glasses or dual-screen mirror systems. These tools allowed researchers to inspect electron-density maps interactively, adjust atomic models in real time, and identify metal-binding geometries with unprecedented precision.
At Leeds, such systems were connected via VAX/VMS and DECstation networks, running early versions of FRODO, O, and TOM molecular modelling software. For many students, these platforms provided their first encounter with immersive molecular visualisation - a transformative experience that turned static diffraction data into tangible, three-dimensional molecular landscapes.
“To visualise a protein structure in three dimensions at that time required both patience and precision - each movement of a carbonyl group was adjusted manually with a trackball or dial box on a Silicon Graphics terminal, viewed through twin polarised displays that brought the molecular world to life.”
Significance of Cation Binding in Annexins
Cation binding in Annexins is crucial for their role in membrane dynamics. Calcium bridges acidic residues to phospholipid head groups, promoting adhesion and curvature stabilisation. This underlies functions such as exocytosis, endocytosis, and anticoagulant activity.
Lanthanum, with its larger ionic radius and higher charge density, serves as an experimental analogue that helps visualise these binding interactions crystalographically.
Such studies not only enhance understanding of Annexin function but also contribute to broader insights into calcium signalling, membrane repair, and protein–lipid interactions.
Conclusion
The study of cation binding in Annexin V highlights how small ions can govern large-scale biological phenomena. The interplay between metal coordination, protein conformation, and membrane interaction exemplifies structural biology’s power to unify chemical and physiological perspectives.
From these early crystallographic investigations emerged principles that now inform modern calcium-signalling biology and the development of biomimetic materials and medical diagnostics.
Afterword (2025 Reflection)
Since 1993, the Annexin family has grown to include over a dozen identified members, each with specific cellular functions ranging from apoptosis to vesicle trafficking. Advances in cryo-electron microscopy, molecular dynamics, and calcium imaging have validated many of the predictions first explored in this essay.
Annexin V is now widely used in medical diagnostics as a marker for early apoptosis through its selective binding to phosphatidylserine—a remarkable translation of biophysical insight into clinical practice.
The questions first posed in this Leeds project continue to resonate in modern structural biology: how do ions, proteins, and membranes coordinate to produce life’s most fundamental movements?
References
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Bewley, M.C., Boustead, C., Walker, J.H., Waller, D.A. and Huber, R. (1992) ‘Crystal structure of chicken Annexin V,’ Unpublished research paper, University of Leeds and Max-Planck Institute.
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Huber, R., et al. (1990) ‘Structure of human Annexin V and identification of lanthanum-binding sites,’ The EMBO Journal, 9(12), pp. 3867–3874.
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Huber, R., et al. (1990) ‘Lanthanum-binding and crystal rearrangement in Annexin V,’ FEBS Letters, 275(1–2), pp. 15–21.
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Huber, R., et al. (1992) ‘Annexin structures and functions,’ Journal of Molecular Biology, 223, pp. 683–704.
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Kretsinger, R.H. (1987) ‘Calcium-binding proteins,’ Cold Spring Harbor Symposia on Quantitative Biology, 52, pp. 499–510.
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Strynadka, N.C.J. and James, M.N.G. (1989) ‘Structural aspects of calcium binding in proteins,’ Annual Review of Biochemistry, 58, pp. 951–980.
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Swain, A.L., Kretsinger, R.H. and Amma, E.L. (1989) ‘Calcium coordination geometries,’ Journal of Biological Chemistry, 264(28), pp. 16620–16628.
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Voet, D. and Voet, J.G. (1990) Biochemistry. New York: Wiley.
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Walker, J.H., et al. (1992) ‘Phospholipid-binding properties of Annexin V,’ Biochemical Society Transactions, 20, pp. 828–833.
Appendix 1 – Glossary of Key Terms
| Term | Definition |
|---|---|
| Annexin | A family of calcium-dependent phospholipid-binding proteins involved in membrane dynamics and signalling. |
| Cation | A positively charged ion, such as Ca²⁺ or La³⁺, which can form coordinate bonds with proteins. |
| Coordination Geometry | Spatial arrangement of atoms or ligands around a central metal ion. |
| EF-Hand | Helix–loop–helix motif common in calcium-binding proteins. |
| Electron-Density Map | A 3D representation of electron distribution used in crystallography to model atomic positions. |
| Lanthanum (La³⁺) | A trivalent rare-earth metal used as a calcium analogue in structural studies. |
| Phospholipid | A lipid containing a phosphate group, forming the bilayer of cell membranes. |
| Resolution (Γ ngstrΓΆm) | Measure of clarity in X-ray crystallographic data; 1 Γ = 10⁻¹⁰ m. |
| Xentronics Area Detector | Early electronic imaging detector used to record X-ray diffraction patterns. |
| X-ray Crystallography | Technique used to determine atomic structures of macromolecules by analysing diffraction patterns from crystals. |
Appendix 2 – Short Biographies of Scientists Mentioned (Alphabetical by Surname)
Amma, E.L.
American crystallographer known for co-authoring studies on calcium-binding coordination with Kretsinger and Swain. Her structural analyses provided foundational understanding of protein–ion interactions.
Bewley, Maria C.
British structural biologist and crystallographer based at the University of Leeds in the early 1990s. Dr Maria C. Bewley was the principal author of the 1992 study “Crystal Structure of Chicken Annexin V”, completed in collaboration with Christopher Boustead, John H. Walker, David A. Waller, and Robert Huber. Her work contributed significantly to understanding calcium-dependent phospholipid-binding proteins and provided one of the earliest high-resolution structures of an Annexin family member.
Huber, Robert (born 1937)
German biochemist awarded the 1988 Nobel Prize in Chemistry for work on protein crystallography. His research on Annexins provided some of the first structural insights into calcium-dependent membrane binding.
James, M.N.G. (born 1937)
Canadian structural biologist whose research focused on protease and calcium-binding enzyme mechanisms. Co-author of several key reviews on calcium-binding proteins.
Kretsinger, Robert H. (born 1937)
American biochemist who discovered the EF-hand motif, a defining structural feature of calcium-binding proteins. His research clarified the geometric basis of calcium coordination in biological systems.
Strynadka, Natalie C.J. (born 1966)
Canadian structural biologist who worked with James on the crystallographic elucidation of enzyme and calcium-binding structures, later pioneering structural studies of membrane proteins.
Swain, Alan L.
Co-researcher with Kretsinger and Amma, contributing to quantitative analyses of calcium-binding site geometries using X-ray diffraction.
Voet, Donald (born 1941) and Voet, Judith G. (born 1943)
American biochemists and co-authors of Biochemistry, one of the most influential textbooks integrating molecular structure with biological function.
Walker, John H.
British biochemist based at the University of Leeds whose research focused on membrane-associated proteins, especially Annexins and phospholipid-binding dynamics.
Waller, David A.
Leeds-based structural biologist and co-author of studies on Annexin V crystal structure and membrane-binding behaviour.
Disclaimer
The views, interpretations, and reflections expressed in this essay are those of the author and do not necessarily represent the positions of the University of Leeds or any affiliated institution.
Essay: Continuous Wave and Fourier Transform NMR Techniques
A Discussion of Continuous Wave and Fourier Transform Techniques in Nuclear Magnetic Resonance Experiments
Originally written Autumn 1992, BSc (Hons) Molecular Biophysics, University of Leeds
Preface (2025 Edition)
This essay was produced in 1992 during the Spectroscopic Methods in Biophysics module at the University of Leeds. It examined how developments in Nuclear Magnetic Resonance (NMR) instrumentation revolutionised the study of molecular structure.
At that time, Fourier Transform NMR (FT-NMR) was replacing the older Continuous Wave (CW) approach, greatly increasing sensitivity and resolution. The essay sought to explain how both methods operate and why the transition to FT marked a paradigm shift in molecular spectroscopy.
A Discussion of Continuous Wave and Fourier Transform Techniques in NMR Experiments
Introduction
Nuclear Magnetic Resonance (NMR) spectroscopy provides molecular-level insight into structure, motion, and dynamics. Early NMR spectrometers employed the Continuous Wave (CW) method, in which a single monochromatic radio-frequency signal was slowly swept across the spectral range. In the early 1970s, this was superseded by the Fourier Transform (FT) method, where a short, intense pulse simultaneously excites all nuclear frequencies and the resulting signal is mathematically decomposed into its frequency components by the Fourier transform.
The two techniques illustrate the evolution from sequential to parallel data acquisition in physical chemistry.
Instrumentation
CW NMR Spectrometer:
A crystal oscillator generates a stable radio-frequency (RF) field, swept gradually through resonance while the magnetic field remains constant. The signal is monitored using an amplifier and chart recorder. Stability is maintained through field–frequency locking.
FT NMR Spectrometer:
In FT systems, a powerful RF pulse (≈ 1 kW, < 5 ΞΌs) excites all resonant nuclei simultaneously. The resulting free-induction decay (FID) is digitised and processed by a computer that performs the Fourier transform to produce the spectrum.
Modern instruments contain separate transmitter channels for field locking, observation, and decoupling, along with superconducting magnets (1.5 – 12 T) to ensure high field strength and homogeneity. Fine adjustments are achieved using shim coils, which compensate for magnetic gradients and thermal drift.
Sample Preparation and Requirements
NMR samples are usually liquid or solution phase and housed in precision glass tubes. For proton (¹H) studies, 5 mm tubes are typical, while 13 C studies may require 10–12 mm tubes. Because NMR is relatively insensitive, sample concentrations of around 1 % are often necessary.
Spinning the sample at about 15 Hz averages magnetic field inhomogeneities, improving line-shape. Temperature control is maintained by passing pre-heated or pre-cooled nitrogen gas around the sample tube. Reference compounds, such as tetramethylsilane (TMS), provide chemical-shift standards.
CW Technique: Principle and Limitations
In CW NMR, resonance absorption is detected while the magnetic field or RF frequency is slowly varied. Each resonance is observed individually, and a full spectrum may require hundreds of seconds to record.
Because signals are weak, multiple scans are averaged to improve the signal-to-noise ratio, but this process is time-consuming. Resolution is further limited by field instability and mechanical drift in scanning systems. For nuclei less sensitive than ¹H, such as ¹³C, the CW approach becomes impractical.
This slow, sequential process may be likened to “tuning each piano note in turn” to identify its frequency.
Fourier Transform Technique: Principle and Advantages
The FT method replaces frequency scanning with time-domain excitation. A single broadband RF pulse simultaneously perturbs all nuclear spins. As these spins relax, they emit the free-induction decay (FID) signal, which contains the complete frequency information of the system. The spectrometer’s computer applies a Fourier transform to convert this time-domain signal into a frequency-domain spectrum.
Because many signals are captured at once, multiple scans can be accumulated quickly, improving the signal-to-noise ratio in proportion to the square root of the number of scans.
The FT method allows for multinuclear detection (¹H, ¹³C, ¹⁵N, ³¹P), two-dimensional NMR, and advanced pulse sequences. It also enables decoupling experiments, where specific nuclei are selectively irradiated to simplify spectra or reveal coupling constants.
Practical Considerations and Artefacts
The FID must be detected after a short “dead time,” the period immediately following the RF pulse when receiver circuits recover from saturation. Proper tuning and shimming minimise artefacts such as baseline distortion or “ringing.”
Temperature control remains critical: heating may broaden lines by inducing molecular motion, while cooling increases viscosity and relaxation times. The absence of mechanical scanning in FT NMR eliminates drift artefacts common in CW spectra.
Comparative Summary
| Feature | CW NMR | FT NMR |
|---|---|---|
| Data acquisition | Sequential | Simultaneous (time-domain) |
| Speed | Slow (minutes per spectrum) | Rapid (seconds) |
| Sensitivity | Low | High; improved by signal averaging |
| Resolution | Limited by mechanical drift | High; field stability and digital precision |
| Multinuclear capability | Usually ¹H only | Multi-nuclear (¹H, ¹³C, ¹⁵N etc.) |
| Data processing | Analogue | Digital via Fourier transform |
| Applications | Routine chemistry, early biophysics | Modern biomolecular, medical, and solid-state NMR |
Applications in Molecular Biophysics
The rise of FT NMR allowed researchers to analyse large biomolecules such as peptides, nucleic acids, and small proteins in solution. High-field instruments at the Astbury Centre in Leeds were among the first in the UK to explore conformational dynamics using pulse sequences that revealed coupling networks and hydrogen-bond patterns.
The ability to detect nuclei other than ¹H, such as ¹³C and ¹⁵N, provided complementary information to X-ray crystallography, illuminating molecular motion rather than static structure.
Conclusion
The transition from Continuous Wave to Fourier Transform NMR represents a milestone in molecular spectroscopy. CW techniques laid the foundation, but FT methods transformed NMR into a versatile, high-resolution tool for chemical, biological, and medical research.
By capturing all resonances simultaneously and applying computational analysis, FT NMR embodies the very principle that defines modern biophysics: extracting dynamic molecular information from static physical laws.
Afterword (2025 Reflection)
Since 1992, NMR technology has advanced even further with cryoprobes, hypermolar polarisation, and solid-state NMR enabling detailed analysis of entire proteins, membranes, and metabolic networks. Today’s multi-dimensional NMR maps not only static structures but also the motions that underpin biological function—realising, in practice, the very idea A.V. Hill resisted: that even in apparent stillness, molecules “wriggle.”
References (Harvard Format)
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Abraham, R.J., Fisher, J. and Lochinvar, P. (1988) Introduction to NMR Spectroscopy. Chichester: Wiley.
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Derome, A.E. (1987) Modern NMR Techniques for Chemistry Research. Oxford: Pergamon Press.
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Harris, R.K. (1983) NMR Spectroscopy: A Practical Approach. London: Longman.
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Lauterbur, P.C. (1973) ‘Image formation by induced local interactions: Examples employing NMR,’ Nature, 242, pp. 190–191.
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WΓΌthrich, K. (1986) NMR of Proteins and Nucleic Acids. New York: Wiley-Interscience.
Appendix 1 – Glossary of Key Terms
| Term | Definition |
|---|---|
| Chemical Shift | Variation in NMR resonance frequency caused by the local electronic environment of a nucleus. |
| CW (Continuous Wave) NMR | Traditional NMR method using a continuous RF signal scanned across resonance frequencies. |
| Decoupling | Technique in which one type of nucleus is continuously irradiated to remove spin–spin coupling effects. |
| FID (Free Induction Decay) | The time-domain signal emitted by excited nuclei after an RF pulse. |
| Fourier Transform | Mathematical process converting time-domain data into frequency-domain spectra. |
| Homogeneity | Uniformity of the magnetic field across the sample volume. |
| Pulse Sequence | A defined series of RF pulses and delays used to manipulate nuclear spins in NMR experiments. |
| Shim Coils | Auxiliary coils used to correct magnetic field inhomogeneities. |
| Signal-to-Noise Ratio | Measure of spectral clarity; improves with repeated signal averaging. |
| TMS (Tetramethylsilane) | Standard reference compound for defining zero chemical shift in ¹H and ¹³C NMR. |
Appendix 2 – Short Biographies of Scientists Mentioned (Alphabetical by Surname)
Abraham, Raymond J. (1931–2014)
British physical chemist and NMR pioneer, known for integrating quantum-chemical calculations with NMR data to interpret molecular structure. His textbook Introduction to NMR Spectroscopy (1988) became a standard reference in chemical education.
Derome, Anthony E. (1942–1990)
Chemist at the University of Cambridge who advanced pulse-programming techniques for FT NMR. His Modern NMR Techniques for Chemistry Research (1987) unified the theoretical and practical aspects of time-domain spectroscopy.
Harris, Robin K. (1939–2022)
British spectroscopist and author of foundational works on NMR methodology. Harris promoted the practical application of FT NMR in both academic and industrial chemistry.
Lauterbur, Paul Christian (1929–2007)
American chemist and 2003 Nobel Laureate in Physiology or Medicine. He discovered magnetic-field gradient imaging using NMR signals, giving rise to Magnetic Resonance Imaging (MRI).
WΓΌthrich, Kurt (born 1938)
Swiss chemist awarded the 2002 Nobel Prize in Chemistry for developing NMR methods to determine the three-dimensional structures of biological macromolecules in solution.
Disclaimer
The views, interpretations, and reflections expressed in this essay are those of the author A. Kariyawasam and do not necessarily represent the positions or opinions of staff at the University of Leeds or any affiliated institution.


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