Mechanism of substrate recognition in cholesterol oxidase: Reaction with steroid enantiomers.
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Accession number;99A0228216
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| Title;Mechanism of substrate recognition in cholesterol oxidase: Reaction with steroid enantiomers. |
| Author;
KITAMOTO DAI
(National Inst. Materials and Chemical Res.)
YANAGISHITA HIROSHI
(National Inst. Materials and Chemical Res.)
BLELLMANN J F
(Univ. Louis Pasteur, Strasbourg, Fra)
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Journal Title;Abstracts. Symposium on Biofunctional Chemistry
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Journal Code:L0836A
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ISSN:
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VOL.13th;NO.;PAGE.82-84(1998)
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| Figure&Table&Reference; |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;We were interested in probing how much conformational flexibility was available to the substrate in the active site of cholesterol oxidase(CO). Thus, we undertook the synthesis of testosterone derivatives, androsta-4,9(11)-diene-3.BETA.,17.BETA.-diol (1), androsta-5,9(11)-diene-3.BETA.,17.BETA.-diol (2), ent-androsta-4,9(11)-diene-3.BETA.,17.BETA.-diol (3), ent-androsta-5,9(11)-diene-3.BETA.,17.BETA.-diol (4) and did their assay with different CO. ALL the alcohols 1-4 were oxidized to 3-keto-4-ene steroids by CO. Surprisingly, the oxidation rate of allyl alcohol 1 was approximately two times larger than that of its enantiomer 3 with any CO tested. In addition, there was not much difference in Vmax value between 1 and 3, while a significant difference in Km, value between the two enantiomers. Almost the same result was obtained for homoallyl alcohol 2 and 4. These results would indicate that the unnatural enantiomers 3, 4 are able to bind efficiently to the active site of CO in the mode of "upside-down", considering that all the two hydroxyl groups at C-3 and C-17 and two methyl groups at C-18 and C-19 have the same configuration with respect to the plane of the steroid ring system like cholesterol. (author abst.) |
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