Malcolm Dixon

Education and early life

Dixon was born in Cambridge, UK to Allick Page Dixon and Caroline Dewe Dixon (née Mathews). He received his PhD in 1925, for research supervised by Frederick Gowland Hopkins at the University of Cambridge.

Research and career

Dixon's research investigated the purification of enzymes and the enzyme kinetics of enzyme-catalyzed reactions. He studied the oxidation of glutathione and other thiols by molecular oxygen and measured the redox potential of the thiol-disulfide system, also establishing that the oxidation of glutathione was catalyzed by trace metals. He investigated xanthine oxidase, and thereby elucidated many aspects of the chemistry of dehydrogenases. He showed that the hydrogen peroxide formed in the reaction of xanthine oxidase with molecular oxygen inactivated the enzyme and that the inhibition could be relieved by the addition of catalase, thus helping to establish a biochemical role for the latter enzyme. Dixon published a series of papers on D-amino acid oxidase, detailing the kinetics and thermodynamics of association of the coenzyme with the apoprotein, the substrate and inhibitor specificity, and the effect of pH on the kinetic constants.

Dixon was an expert on the theory and use of manometers. In 1931, he collaborated with David Keilin and Robin Hill to determine the first absorption spectrum of a cytochrome, cytochrome c. Dixon studied the chemistry of lachrymators and mustard gas and proposed a phosphokinase theory to explain their mode of action.

Awards and honours

Dixon was elected a Fellow of the Royal Society (FRS) in 1942 and became a Fellow of King's College, Cambridge in 1950. He died in Cambridge in 1985.