Krebs' research involved enzymes, the protein molecules that catalyze biochemical reactions. While at the University of Washington, Krebs worked with Edmond Fisher and the pair discovered the reversible phosphorylation of glycogen phosphorylase which serves to activate the enzyme. Glycogen phosphorylase is the enzyme that removes monosacharides from glycogen (the polysacharide used to store glucose for future use) so that they can be broken down into energy. Glycogen phosphorylase exists in two forms A and B. The Cori's had found that form B is inactive unless it is in the presence of adenosine monophosphate (AMP) and that form A is active without AMP. They also knew from the experiments of the Cori's that the active A form degrades into the inactive B form. Krebs and Fischer discovered that the B form is reversibly phosphorylated (phosphate is added to the protein molecule) converting it into the A form, which causes it to be activated so that it can break down glycogen. This was the first discovery of reversible phosphorylation which is a ubiquitous mechanism that serves as a means of activating many enzymes and transducing biochemical signals. For their discovery of the regulation of glycogen phosphorylase by phosphorylzation Krebs and Fischer were awarded the 1992 Nobel Prize in medicine and physiology.
Krebs died on December 9, 2009.
Fischer, Edmond H.; "Edwin G. Krebs (1918-2009)"; in Biographical Memoirs; 2010; National Academy Press
Krebs, Edwin G.; "Nobel Autobiography"
Edwin G. Krebs Wikipedia Entryhttp://en.wikipedia.org/wiki/Edwin_G._Krebs