| Autor: |
I. Matysková, L. Matyska, J. Kovář |
| Rok vydání: |
1986 |
| Předmět: |
|
| Zdroj: |
Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology. 871:302-309 |
| ISSN: |
0167-4838 |
| Popis: |
Investigation of the hysteretic behaviour of d-3-hydroxybutyrate dehydrogenase ((R)-3-hydroxybutanoate: NAD+ oxidoreductase, EC 1.1.1.30) by stopped-flow revealed that the aggregation of enzyme molecules is responsible for the observed time-dependent increase in enzyme activity. The aggregation is triggered by the association of NAD (or NADH) to the enzyme; the nicotinamide ring of the coenzyme seems to be responsible for these phenomena. The hysteretic behaviour of this enzyme is influenced by temperature; the coenzyme-induced aggregation is suppressed at temperatures below 10°C. The steady-state kinetics of the aggregated enzyme (at pH 7 and 25°C) obey the ordered mechanism, the binding of both coenzymes precedes that of both substrates. d-Lactate and dl-2-hyroxybutyrate are relatively strong substrate-competitive inhibitors; ADP-ribose inhibits competitively with respect to the coenzyme. On the other hand, ADP (or AMP) activates essentially at concentrations up to 0.3 mM, higher concentrations of this ligand bring about a slight inhibition of the enzyme. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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