Document Detail

Mechanistic study of an improbable reaction: alkene dehydrogenation by the delta12 acetylenase of Crepis alpina.
MedLine Citation:
PMID:  12940747     Owner:  NLM     Status:  MEDLINE    
The mechanism by which the fatty acid acetylenase of Crepis alpina catalyzes crepenynic acid ((9Z)-octadeca-9-en-12-ynoic acid) production from linoleic acid has been probed through the use of kinetic isotope effect (KIE) measurements. This was accomplished by incubating appropriate mixtures of regiospecifically deuterated isotopomers with a strain of Saccharomyces cerevisiae expressing a functional acetylenase. LC/MS analysis of crepenynic acid obtained in these experiments showed that the oxidation of linoleate occurs in two discrete steps, since the cleavage of the C12-H bond is very sensitive to isotopic substitution (k(H)/k(D) = 14.6 +/- 3.0) while a minimal isotope effect (k(H)/k(D) = 1.25 +/- 0.08) was observed for the C13-H bond breaking step. These data suggest that crepenynic acid is produced via initial H-atom abstraction at C12 of a linoleoyl substrate. The relationship between the mechanism of enzymatic acetylenation and epoxidation is discussed.
Darwin W Reed; Devin R Polichuk; Peter H Buist; Stephen J Ambrose; Robert J Sasata; Christopher K Savile; Andrew R S Ross; Patrick S Covello
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  125     ISSN:  0002-7863     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2003 Sep 
Date Detail:
Created Date:  2003-08-27     Completed Date:  2003-10-21     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  10635-40     Citation Subset:  IM    
NRC Plant Biotechnology Institute, 110 Gymnasium Place, Saskatoon, Saskatchewan, Canada S7N 0W9.
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MeSH Terms
Alkenes / chemistry,  metabolism*
Alkynes / chemistry,  metabolism
Crepis / enzymology*
Fatty Acid Desaturases / chemistry,  metabolism*
Linoleic Acids / chemistry,  metabolism
Reg. No./Substance:
0/Alkenes; 0/Alkynes; 0/Linoleic Acids; EC 1.14.19.-/Fatty Acid Desaturases; EC 1.14.99.-/acetylenase

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