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Studies on the Metabolism of Unsaturated Fatty Acids. IX. Stereochemical Studies of the Reaction Catalyzed by trans-2-Enoyl-Coenzyme A Reductase of Escherichia coli1
- Source :
- The Journal of Biochemistry. 92:1649-1654
- Publication Year :
- 1982
- Publisher :
- Oxford University Press (OUP), 1982.
-
Abstract
- The steric course of the reaction catalyzed by NADPH-dependent trans-2-enoyl-CoA reductase from Escherichia coli was investigated. trans-2-[6,7,8-2H7]Octenoyl-CoA was synthesized as a substrate and incubated with partially purified trans-2-enoyl-CoA reductase in the presence of 4R- or 4S-[4-2H1]NADPH. The deuterium-labeled octenoyl-CoA was also incubated with the reductase in the presence of NADPH in 2H2O. Aliquots of octanoic acids formed were analyzed, after esterification, by gas chromatography-mass spectrometry (GC-MS) to demonstrate that the pro-4R hydrogen of NADPH was incorporated into the C-3 position of octenoyl-CoA and that hydrogen from water was introduced into the C-2 position of octenoyl-CoA. The remaining portions of octanoic acids isolated from the incubation mixtures were converted to their CoA esters by the action of acyl-CoA synthetase, and they were dehydrogenated by treatment with acyl-CoA oxidase, which had previously been shown to catalyze the anti-elimination of the pro-2R and pro-3R hydrogen atoms of acyl-CoA. The deuterium contents of the products were also analyzed by GC-MS, and the results indicated that the reduction catalyzed by NADPH-dependent trans-2-enoyl-CoA reductase occurred by an anti-addition of hydrogen via a 2-Re, 3-Re attack on the trans-double bond of the substrate.
Details
- ISSN :
- 17562651 and 0021924X
- Volume :
- 92
- Database :
- OpenAIRE
- Journal :
- The Journal of Biochemistry
- Accession number :
- edsair.doi...........2ab7b3dbde45dbf0507adc8c8d42c955