Inhibition of rat alpha-reductases by finasteride: evidence for isozyme differences in the mechanism of inhibition
| Autor: | Kenneth P. Ellsworth, Stefan Andersson, Georgianna Harris, Wayne M. Geissler, Herbert G. Bull, B. Azzolina |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Protein Denaturation
Hot Temperature Endocrinology Diabetes and Metabolism Recombinant Fusion Proteins Clinical Biochemistry Biochemistry Isozyme Rats Sprague-Dawley 5 Alpha-Reductase Inhibitor chemistry.chemical_compound Endocrinology 5-alpha Reductase Inhibitors 3-Oxo-5-alpha-Steroid 4-Dehydrogenase medicine Animals Enzyme Inhibitors Molecular Biology Ternary complex chemistry.chemical_classification COS cells biology Finasteride Cell Biology Rats Isoenzymes Kinetics Enzyme Mechanism of action chemistry Enzyme inhibitor COS Cells biology.protein Molecular Medicine medicine.symptom NADP |
| Zdroj: | The Journal of steroid biochemistry and molecular biology. 61(1-2) |
| ISSN: | 0960-0760 |
| Popis: | The mechanism of inhibition of the rat types 1 and 2 5alpha-reductase by finasteride was investigated using recombinantly expressed enzymes. These studies revealed that finasteride is a potent, reversible inhibitor of the rat type 1 5alpha-reductase with Ki=10.2+/-1.3 nM. Finasteride is a potent inhibitor of the rat type 2; however, in this case the compound binds to the type 2 isozyme-NADPH complex to form a ternary complex with Ki=1.19+/-0.10 nM, which then rearranges to a high affinity complex (E:I) with a pseudo first order rate constant of 1.62+/-0.22 x 10(-3)/s. The second order rate constant is k3/Ki=1.37+/-0.31 x 10(6) M/s. Heat denaturation of the (type 2 enzyme:inhibitor) complex releases dihydrofinasteride and presumably the NADP+-adduct previously identified with the human 5alpha-reductases. The effects of finasteride were also studied in intact COS cells transiently expressing the rat types 1 and 2 5alpha-reductase. Results with whole cell assays confirm differences in mechanism of inhibition of rat types 1 and 2 5alpha-reductase by finasteride. |
| Databáze: | OpenAIRE |
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