Enzyme inhibition during the conversion of squalene to cholesterol
| Autor: | Saul J. Needle, Amin Dilip, Sheng Yuh Tang, Glenda E. Bilder, Helen Galczenski, Linda Merkel, Donald Lewis, Camilo J. Rojas, Mark H. Perrone, Marie M. Gleason |
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| Rok vydání: | 1995 |
| Předmět: |
Male
Squalene Oxidoreductases Acting on CH-CH Group Donors Clinical Biochemistry Biology Biochemistry Piperazines Rats Sprague-Dawley Lanosterol chemistry.chemical_compound Dehydrocholesterols Endocrinology Desmosterol Animals Enzyme Inhibitors Molecular Biology Pharmacology chemistry.chemical_classification Benzoxazoles Cyclohexylamines Cholesterol Organic Chemistry Metabolism Sterol Rats Farnesyl-Diphosphate Farnesyltransferase Enzyme chemistry Enzyme inhibitor biology.protein lipids (amino acids peptides and proteins) Oxidoreductases |
| Zdroj: | Steroids. 60:475-483 |
| ISSN: | 0039-128X |
| DOI: | 10.1016/0039-128x(95)00054-t |
| Popis: | Two separate enzymatic assays were developed in order to test the selectivity of inhibitors in cholesterol biosynthesis. One assay detects inhibition of delta 5.7-sterol delta 7-reductase, the enzyme involved in the conversion of 7-dehydrocholesterol to cholesterol. Delta 5.7-Sterol delta 7-reductase was inhibited by both RPR 101821, a protonated cyclohexylamine, and BM 15.766, a piperazine derivative, with IC50 values of 1 microM. The second assay detects accumulation of any of five intermediates (squalene oxide, squalene dioxide, lanosterol, desmosterol, and 7-dehydrocholesterol) upon inhibition of enzymes catalyzing reactions in the conversion of squalene to cholesterol. In this assay, inhibition data were most accurate when control assays exhibited a conversion of squalene to cholesterol in the order of 50%. The time required to attain 50% conversion of squalene to cholesterol was 6 h. Given a high inhibitor to substrate concentration ratio and the possible values of Ki, kon, and koff for the reaction between enzymes and inhibitor to form enzyme-inhibitor complexes, it was predicted that in the presence of inhibitors, intermediate accumulation could still be observed after 6 h incubation. The experimental results were in agreement with this prediction. |
| Databáze: | OpenAIRE |
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