Brian was educated at Rossall School and Cambridge University. He graduated with distinction in Natural Sciences and his interest in mitochondria began during his PhD studies with Sam Perry in Cambridge in the early 1950s. He was awarded a research fellowship at Trinity College which, perhaps surprisingly, supplemented his income during his national service in the RAF. During this time he received training in electronics which stood him in good stead in his later research.
After his return to Cambridge he began, together with his PhD student Tony Crofts, a series of original and important studies on factors affecting respiration and oxidative phosphorylation in isolated mitochondria. In 1964 he was invited by Professor Philip Randle to join him as one of the founders of the new Bristol Biochemistry Department. The research he began in Cambridge was continued successfully in Bristol. As a result Brian was awarded the prestigious Biochemical Society Colworth Medal in 1965 and also a medal from the Société de Chemie Biologique.
At that time, facilities for bioenergetics research at Bristol were scarce. Brian was active in developing and constructing equipment that allowed the continuous and simultaneous recording of various mitochondrial activities, a major advance on techniques then available. These methodologies were widely taken up and proved essential for the work of his own group and other members of this Department, as well as groups elsewhere. Double beam spectrophotometers built to his design in the Medical School workshops were sold to other laboratories, and other devices were taken up commercially.
From 1965 Brian recruited and trained a number of very capable PhD students from Bristol and elsewhere, and began his ground-breaking work on the permeability properties of isolated mitochondria.
His group was able to make continuous indirect measurements of the entry of metabolic substrates into isolated mitochondria. This work was complemented by direct measurements of substrate and ion transport using radiolabelled substrates and also ion-selective electrodes. The result was the discovery and characterisation of some eight specific substrate transport systems in the mitochondrial membrane, a concept that was completely new at the time and had great implications for the understanding of cell metabolism and ATP synthesis.
Another important aspect of this work was the characterisation of the effects of compounds such as uncouplers and some cyclic antibiotics which induced hydrogen ion and cation permeability in model membrane systems and the use of this data to interpret the effects of these compounds on substrate transport and oxidative phosphorylation in mitochondria. Taken together, these findings confirmed predictions of the chemiosomotic hypothesis of oxidative phosphorylation for which Peter Mitchell was awarded the Nobel prize in 1978 and were important in the eventual general acceptance of this hypothesis. This work helped to establish the Bristol Biochemistry Department as a leading international centre of bioenergetics research.
This period was one of great activity in Brian’s laboratory. He was an inspiring energetic and creative force. Post-doctoral workers came from Europe and further afield on visits to learn the techniques and principles he had developed. Many of his own PhD students later established successful academic careers in the USA and elsewhere, and the work he originated was widely taken up and developed in other laboratories.
In 1975 Philip Randle moved to Oxford and Brian was appointed Head of the Biochemistry Department, which had by now greatly expanded. He held this position until his retirement in 1995. This was a period of rapid change and advancement in biochemistry with the advent of DNA sequencing and recombinant DNA technology. By a series of successful and appropriate lectureship appointments he ensured that the Department was fully able to expand into these areas. Expertise in protein structure, protein engineering, and X-ray crystallography were among other specialities fostered to support the existing strengths of the Department. His colleagues remember him as being sharp in academic discussions and decisive in the allocation of resources. He continued and diversified his own interest in bioenergetics and his last papers were concerned with characterisation of the proton-linked NADPH oxidase in neutrophils, white blood cells involved in resistance to infection.
Brian Chappell was immensely respected in both the UK and international biochemistry community, and as Head of Department he provided a very prominent and eminent lead over a period in which Bristol Biochemistry developed a truly international reputation.
Brian and his wife Josephine were very hospitable and enjoyed entertaining students and visitors at their home. He was an ambitious and successful cook and delighted in exhibiting his skills. Indeed, to him cooking was both an art and a science. The barbecues which took place at intervals on the terrace outside his laboratory in the early days were a pleasant surprise to some visitors.
Brian is survived by Josephine, his wife of 59 years, and by two sons, two daughters and his grandchildren, to all of whom he was devoted.