title: Modification of glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides with the 2',3'-dialdehyde derivative of NADP+ (oNADP+).
abstract: Glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides is irreversibly inactivated by the 2,3'-dialdehyde of NADP+ (oNADP+) in the absence of substrate. The inactivation is first order with respect to NADP+ concentration and follows saturation kinetics, indicating that the enzyme initially forms a reversible complex with the inhibitor followed by covalent modification (KI = 1.8 mM). NADP+ and NAD+ protect the enzyme from inactivation by oNADP+. The pK of inactivation is 8.1. oNADP+ is an effective coenzyme in assays of glucose-6-phosphate dehydrogenase (Km = 200 microM). Kinetic evidence and binding studies with [14C] oNADP+ indicate that one molecule of oNADP+ binds per subunit of glucose-6-phosphate dehydrogenase when the enzyme is completely inactivated. The interaction between oNADP+ and the enzyme does not generate a Schiff's base, or a conjugated Schiff's base, but the data are consistent with the formation of a dihydroxymorpholino derivative.
mesh_terms: D000596:Amino Acids; D055598:Chemical Phenomena; D002621:Chemistry; D004396:Coloring Agents; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D007700:Kinetics; D007934:Leuconostoc / Q000201:enzymology*; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D014227:Triazines / Q000378:metabolism
chemical_list: D000596:Amino Acids; D004396:Coloring Agents; D014227:Triazines; D009243:NAD; D009249:NADP; C038805:2',3'-dialdehyde NADP; D005954:Glucosephosphate Dehydrogenase