Effects of substrate and inhibitor binding on thermal and proteolytic inactivation of rat liver transhydrogenase
| Autor: | John F. Blazyk, Dominique Lam, Ronald R. Fisher |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
chemistry.chemical_classification
Protein Denaturation Binding Sites Hot Temperature Substrate (chemistry) Mitochondria Liver NAD Biochemistry Rats Kinetics Enzyme Drug Stability chemistry Animals NADH NADPH Oxidoreductases Nucleotide NAD+ kinase Submitochondrial particle Binding site Thermolabile NADP Peptide Hydrolases Protein Binding Thermostability |
| Zdroj: | Biochemistry. 15:2843-2848 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi00658a022 |
| Popis: | The thermostability and proteolytic inactivation of rat liver submitochondrial particle transhydrogenase was studied in the presence of pyridine dinucleotide substrates and a variety of divalent metal and nucleotide inhibitors. Relative to the unliganded enzyme, the NADPH-enzyme complex was more thermostable and showed a twofold greater rate of tryptic inactivation, while the NADP+-enzyme complex was more thermolabile and only slightly more susceptible to tryptic inactivation. Neither NAD+ nor NADH significantly affected thermostability or proteolysis. Similar effects of these ligands were observed for the non-energy-linked and energy-linked transhydrogenase reactions, indicating that both activities are catalyzed by the same enzyme. In thermal experiments, acetyl-CoA, 2'-AMP, and NMNH stabilized, palmitoyl-CoAlabilized, and dephospho-CoA, CoA, NMN+, and 5'-AMP had little effect on enzyme stability. Tryptic inactivation was inhibited by 2'-AMP and NMN+ but was not influenced by the other nucleotide inhibitors. Divalent metal ion inhibitors (Mg2+, Ca2+, Mn2+, Ba2+, and Sr2+) stabilized transhydrogenase against thermal inactivation and promoted tryptic inactivation. |
| Databáze: | OpenAIRE |
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