Molecular chaperones protect against glycation-induced inactivation of glucose-6-phosphate dehydrogenase.

Glucose-6-phosphate dehydrogenase is inactivated slowly by reaction with sugars (glycation), a process thought to be important in the development of diabetic complications. A major protein from the ocular lens, alpha-crystallin. which exhibits some chaperone-like properties, protects against this inactivation. The well-known molecular chaperone GroEL (chaperonin 60 from Escherichia coli) also protects. On a molar basis, alpha-crystallin is better than GroEL at protecting against glycation-induced inactivation of glucose-6-phosphate dehydrogenase. The relative amounts of enzyme/chaperone indicate that each molecule of alpha-crystallin binds two molecules of the damaged enzyme. This supports the view that alpha-crystallin has a chaperone-like structure as well as a chaperone-like function.