Modification of glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides with the 2',3'-dialdehyde derivative of NADP+ (oNADP+)
| Autor: | H R Levy, B J White |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
chemistry.chemical_classification
biology Stereochemistry Substrate (chemistry) Dehydrogenase Cell Biology biology.organism_classification Biochemistry Cofactor chemistry.chemical_compound Enzyme chemistry Leuconostoc mesenteroides biology.protein Glucose-6-phosphate dehydrogenase Enzyme kinetics NAD+ kinase Molecular Biology |
| Zdroj: | Journal of Biological Chemistry. 262:1223-1229 |
| ISSN: | 0021-9258 |
| DOI: | 10.1016/s0021-9258(19)75775-5 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|