Krebs, Edwin Gerhard (1918- )

US physician who was awarded the Nobel Prize for Physiology or Medicine in 1992, with Edmond Fischer, for their work in isolating and describing the action of the enzyme responsible for reversible protein phosphorylation, a major biological control mechanism.

Discoveries Krebs and Fischer characterized a group of enzymes, called protein kinases, that change proteins from their inactive to active form by triggering the chemical bonding of a phosphate group to the protein. This phosphorylation is the underlying switch that starts and stops a variety of cell functions, from breakdown of fats to the generation of chemical energy in response to hormonal and other signals. They determined adenosine triphosphate (ATP), a nucleotide molecule found in all cells, to be the energy-transporting compound which donated the phosphate group.

Working on muscle tissue, they also showed that protein phosphorylation was the underlying mechanism that accounted for the reversible modification of glycogen phosphorylase.

Life Krebs was born in Lansing, Iowa, and graduated from the University of Illinois. He later joined the staff of the medical school of the University of Washington, where in the 1950s he began working with Fischer on the fundamental chemical reactions that regulate cell metabolism.

Importance of his work Hundreds of protein kinases have been found since their discovery and it has been estimated that perhaps 1% of genes encode one sort of protein kinase or another. Indeed it is now evident that phosphorylation controls virtually every important reaction in cells and provides the basis for understanding how integrated cellular behaviour is regulated by both intracellular control mechanisms and extracellular signals.