King's College London

Born in the East End of London in 1930, the son of Yiddish-speaking Polish Jewish immigrants, Professor Baum studied his undergraduate degree in Chemistry (for which he received first-class honours) at the University of Birmingham. He stayed there to complete his PhD research under the supervision of G.A. Gilbert, pioneering methods for separating the two components of starch – amylose and amylopectin – under anaerobic conditions. Published in Chemistry and Industry (1954), the Journal of the Chemical Society (1955) and the Journal of Colloid Science (1956), this work remains widely cited since the ability to fractionate starch is now fundamental to food processing, crop breeding, biodegradable packaging and pharmaceutical manufacturing.

As a Post-Doc Professor Baum worked first at the Institute for Enzyme Research at the University of Wisconsin where he published a landmark series of papers with H.R. Mahler and G. Hübscher on uricase, the enzyme that breaks down uric acid and is the core determinant of gout. This work on uric acid metabolism continues to underpin both a routine diagnostic blood test and a class of therapeutic drugs still prescribed today.

After a further two years at Cardiff University, he joined the Royal Free Hospital School of Medicine in London as a Lecturer and then Senior Lecturer. It was there in 1967 that with three other colleagues (J.S. Rieske, H.I. Silman and S.H. Lipton) he published a paper proposing the idea of electron bifurcation: electrons splitting along two separate paths within a single enzyme complex. This research fed directly into chemiosmotic theory, which won Peter Mitchell the 1978 Nobel Prize in Chemistry, and was cited by Mitchell in many of his own papers.

While Professor Baum’s research interests started out in bioenergetics, he went on to focus on many molecular aspects of medicine, particularly autoimmune and inflammatory diseases and ageing. He became a Fellow of the Royal Society of Chemistry in 1970 and of the Institute of Biology (now the Royal Society of Biology) in 1982. He received his first professorship at Chelsea College, which merged with King’s in 1987. At King’s he went on to hold several leadership roles including Head of the Department of Biochemistry, Dean of Life Sciences, and Head of the School of Life, Basic Medical and Health Sciences.

It was at this time that Professor Mark Peakman, now an Adjunct Professor of Clinical Immunology at King’s, met Professor Baum as he was developing his interest in molecular mimicry as a root cause of autoimmune and inflammatory diseases. He recalls: “Harold would do what he called ‘tinkering’ – looking for amino acid sequences in HLA that mimicked self or microbial antigens, setting up hypotheses around 2- and 3-way mimicry. I don’t think we could call it AI, but he was using the most powerful computing technology available to conduct searches, which might take days to complete and even longer to pore over. Typically the sequences were written by hand on a piece of paper, and we would discuss the implications and experiments we could do to test the hypotheses.”

Professor Barry Halliwell, now Senior Advisor (Academic Appointments and Research Excellence) in the Office of the Provost at the National University of Singapore, also worked with Professor Baum at this time, and they published four papers together. He describes Professor Baum as “a ball of fire, always active, running around and interested in everything – all aspects of science and many aspects of non-scientific areas from music to pottery. He was an expert on liver metabolism, both from the clinical side in collaboration with the Liver Unit at King’s College Hospital and from the basic Biochemistry approach.”

A generous and wise teacher and mentor, Professor Baum positively impacted the lives and careers of many students.

Professor Daksha Trivedi, now a Professor of Applied Health Research at the University of Hertfordshire worked with Professor Baum in the early 1980s and notes that: “He saw great potential in me, even when I was still learning to see it myself - a gift that lasted far beyond my doctoral years. I recall walking into his office with numerous questions about my research and his look told me he had already anticipated them. Years later, a professor myself, I realise the meaning of his wise counsel and find myself passing on the same words of wisdom: clarity often arrives when we stop chasing it.”

Dr. Jeya Chelliah, one of his former PhD students now based in the Department of Biochemistry at King’s reflects: “Professor Baum combined scientific distinction with remarkable generosity as a mentor. His expertise in mitochondrial biology earned him international recognition, but what I admired most was his dedication to developing young scientists. He had an exceptional ability to encourage independent thinking while providing thoughtful guidance and unwavering support.

“One of Professor Baum's greatest strengths was his willingness to look beyond conventional academic backgrounds. Coming from a veterinary medicine education in Sri Lanka, I was given the opportunity to pursue doctoral research under his supervision because he believed in potential rather than pedigree. That confidence transformed the course of my career and opened doors that otherwise might never have been available to me.”

In the same way, Professor Dimitrios P. Bogdanos, Professor of Medicine and Autoimmune Diseases and Vice Rector at the University of Thessaly in Greece describes Professor Baum as “an inspiration, a mentor, and one of the most influential figures in my professional life”, acknowledging that “his belief in me and his unwavering support helped shape the course of my career, first in the UK, then in the USA, and later in Greece. He gave me opportunities, guidance, and encouragement at critical moments, and I can say without hesitation that my professional journey would have been profoundly different without him.”

Professor Diego Vergani, Emeritus Professor of Liver Immunopathology at King’s and a friend and collaborator of Professor Baum adds: “I first met Harold Baum while examining King’s medical students in our respective disciplines in the late ’90s. We became close while reading the students’ essays and commenting on how brilliant some of them were. Our common interests in teaching and science led to a sound friendship between our families and a fruitful scientific collaboration resulting in several joint publications. My wife Giorgina (also an Emeritus Professor of Paediatric Hepatology at King’s) and I grew to very much appreciate and admire his all-encompassing knowledge and interests, including his artistic accomplishments and love of nature. His painting (below) is of a seaside location we loved and visited together.”

On his retirement in 1996 Professor Baum became a Visiting Professor and Professor Emeritus firstly for the Division of Life Sciences, and from 2004 at the School of Medicine, but also internationally at the University of Nairobi in Kenya, the Universities of Nskukka and Ahmadu in Nigeria, and at universities in Malaysia, Kuwait, Singapore, Japan, Italy and the USA.

As well as being a gifted and enthusiastic teacher, Professor Baum was also a brilliant science communicator with a rare talent for turning difficult biochemical concepts into engaging learning experiences, including setting them to music. As the author of the Biochemist’s Songbook, he gave a memorable performance on BBC Nationwide in 1982 singing about biochemical pathways, and afterwards quipping that "there's more information in many of my songs than you'll find it most textbooks!"

As well as his students, Professor Baum inspired the next generation of his own family (his son, daughter and two of his nephews) to follow in his footsteps and pursue careers in the Life Sciences. His nephew, Professor Buzz Baum, now a biologist, explains: “Although I felt awed by his brilliance and often failed to follow the details of his flights of intellect, the twinkle in his eye when discussing his latest research made science seem a light-hearted and joyful thing. He was never self-important, overly critical, or pedantic. Instead, he took delight in seeking to understand the magic and wonder of the natural world in all its intricacies. His love of it was infectious.”

Michael Baum, a surgical oncologist specialising in breast cancer treatment and Professor Emeritus of Surgery formerly based at King’s, is Harold Baum’s only surviving sibling. He recalls: “I was in awe of his ‘genius’ as a polymath, who seemed to know everything about everything. I learnt more from him than at school, including about subjects like ‘scientific philosophy’ and ‘ethical philosophy’. As I grew older, the seven-year age gap shrunk, and he became my best friend. He was sweet and kind in nature, and never patronising to those who knew nothing about science.”

Professor Baum’s lifelong passion for science and science communication never waned, and he sat on the BBC’s Programme Advisory Committee on Continuing Education from 1986–89, was a Director of the scientific publishers Taylor & Francis from 1983–2000 and helped establish the Edinburgh Science Festival as Europe’s premier public science event.

Professor Baum’s legacy is not only his significant contributions to biochemistry, mitochondrial research and autoimmunity, but also the countless students and researchers whose careers he influenced through his encouragement and kindness. He showed that scientific rigor and humour could go hand in hand and created learning environments where curiosity flourished and where students felt both challenged and supported. His sharp mind, wit and warmth will be remembered with admiration, gratitude and great affection by all who had the privilege of knowing him.

Professor Baum is survived by his wife of more than 60 years, Glenda Baum and their three children: Professor David Baum, Dr Mandy Baum and Alison Baum OBE.