title: Kinetics of human erythrocyte glucose-6-phosphate dehydrogenase dimers.
abstract: The steady-state kinetics of human erythrocyte glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) dimers were studied by initial rate measurement. These experiments gave intersecting double-reciprocal plots suggesting a ternary complex mechanism with a Km for NADP and glucose 6-phosphate of 11 microM and 43 microM, respectively. These studies were combined with rate measurements in the presence of one product (NADPH), dead-end inhibitors, as well as alternative substrates. The inhibition by NADPH was found to be competitive with respect to both substrates. Alternate substrates experiments gave linear double-reciprocal plots over a wide range of substrate concentrations. The results suggest that the dimeric enzyme follows either a random or a Theorell-Chance mechanism.
authors.affiliation: Department of Chemistry Occidental College, Los Angeles, CA 90041.
authors.forename: S
authors.initials: S
authors.lastname: Birke
authors.forename: H W
authors.initials: HW
authors.lastname: Kim
authors.forename: A
authors.initials: A
authors.lastname: Periclou
authors.forename: B
authors.initials: B
authors.lastname: Schorsch
authors.forename: D
authors.initials: D
authors.lastname: Grouse
authors.forename: C
authors.initials: C
authors.lastname: Craney
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004912:Erythrocytes / Q000201:enzymology*; D019298:Glucose-6-Phosphate; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000097:blood; D005958:Glucosephosphates / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009249:NADP / Q000494:pharmacology; D011485:Protein Binding
chemical_list: D005958:Glucosephosphates; D009249:NADP; D019298:Glucose-6-Phosphate; D005954:Glucosephosphate Dehydrogenase