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The 21-dehydroxylation of corticosteroids: evidence for an enol intermediate and the hydroxylation of steroids by fungal cyto-chrome P450: evidence for a stepwise mechanism

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dc.contributor.author Riemland, Elly. en_US
dc.date.accessioned 2009-07-09T18:49:01Z
dc.date.available 2009-07-09T18:49:01Z
dc.date.issued 1984-07-09T18:49:01Z
dc.identifier.uri http://hdl.handle.net/10464/2093
dc.description.abstract Two enzyme mechanisms were examined: the 21-dehydroxylation of corticosteroids by the anaerobe Eubacterium l en tum, and the hydroxylation of steroids by fungal cytochrome P450. Deuterium labelling techniques were used to study the enzymic dehydroxylation. Corticosteroids doubly labelled (2H) at the C-21 position were incubated with a culture of Eubacterium lentum. It was found that t he enzymic dehydroxylation proceeded with the loss of one 2H f rom C-21 per molecule of substrate. The kinetic isotope ef fect f or the reaction was found to be k~kD = 2. 28. These results suggest that enzyme/substr ate binding in this case may proceed via t he enol form of the substrate. Also , it appears that this binding is, at least in part, the rate determining step of t he reaction. The hydroxylation of steroids by fungal cytochrome P450 was examined by means of a product study. Steroids with a double bond at the A8 (9), ~( lO ), or ~ (ll) position were synthesized. These steroids were then incubated with fungal strains known to use a cytochrome P450 monooxygenase to hydroxylate at positions allylic to these doubl e bonds. The products formed in these incubations indicated that the double bonds had migrated during allylic hydroxylat ion. This suggests that a carbon centred radical or ion may be an intermediate i n the cytochrome P450 cat alytic cycle. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Corticosterone. en_US
dc.subject Steroids. en_US
dc.subject Hydroxylation. en_US
dc.subject Cytochrome P-450. en_US
dc.subject Fungi--Cytology. en_US
dc.title The 21-dehydroxylation of corticosteroids: evidence for an enol intermediate and the hydroxylation of steroids by fungal cyto-chrome P450: evidence for a stepwise mechanism en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Chemistry en_US
dc.degree.level Masters en_US
dc.contributor.department Department of Chemistry en_US
dc.degree.discipline Faculty of Mathematics and Science en_US


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