Walker, John Ernest (1941-...), a British biochemist, shared half the 1997 Nobel Prize for chemistry with Paul Boyer of the United States for their pioneering work on the process of energy production in living cells (see Boyer, Paul Delos). The other half of the 1997 prize was won by Danish biochemist Jens Skou (see Skou, Jens Christian). Walker and Boyer explained the mechanism involved in the production of the chemical adenosine triphosphate (ATP). ATP is essential to life and is involved in the chemical conversion of nutrients into energy that can be used by cells. See Cell; Respiration.