title: Heat-inactivation of liver glucose-6-phosphate dehydrogenase and malic enzyme in 1- and 12-month-old rats.
abstract: The heat-labilities of liver glucose-6-phosphate dehydrogenase and malic enzyme of 1- and 12-month-old rats were observed by incubation of the crude enzymes at 52 and 55 degrees C, respectively. The biphasic heat-inactivation curves were obtained for those enzymes of the 12-month-olds, whereas no biphasic curves were obtained for the enzymes of the 1-month-olds. The age-dependent rapid inactivations of glucose-6-phosphate dehydrogenase and malic enzyme were not relieved by addition of their substrates in the incubation media. However, the rapid age-dependent inactivations of these enzymes disappeared by addition of NADP. It is suggested that the age-dependent heat-inactivation of these enzymes is ascribed to the conformational modification of the proteins.
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D004795:Enzyme Stability; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D006358:Hot Temperature; D008099:Liver / Q000201:enzymology*; D008291:Malate Dehydrogenase / Q000378:metabolism*; D008297:Male; D009249:NADP / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009249:NADP; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase