Walker, John E(rnest) (1941– )

English chemist who with US biochemist Paul D Boyer and Danish biophysicist Jens C Skou shared the Nobel Prize for Chemistry in 1997 for their explanation of the enzymatic process that produces adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate.

ATP synthase is an enzyme that exists in the cells of animals, plants, and bacteria which catalyses the production of the energy producing molecule ATP. ATP is a source of chemical energy in a living organism, which is produced during respiration in animals, and during photosynthesis in plants. ATP fuels the metabolic processes that allow an organism to live. ATP is formed by a chemical reaction between ADP and inorganic phosphate that is catalysed by the enzyme ATP synthase. What was not known was the mechanism by which this reaction occurred.

Walker studied the composition and structure of ATP synthase and found the sequence of amino acids that made up the protein units of the molecule. He went on to determine the three-dimensional structure of the part of the ATP synthase molecule which was responsible for catalysing the ATP formation reaction. His findings supported Boyer's ‘binding change mechanism’ which explained how ATP was formed. Their discovery has significantly increased our knowledge of the how living organisms function.

Walker was born in Halifax, England. He studied for his PhD at the University of Oxford, England, which he received in 1969. He joined the Medical Research Council Laboratory of Molecular Biology, Cambridge, in 1974 and became a senior researcher there in 1982. He was elected to be a fellow of the Royal Society in 1995.