Epimerization of 3-hydroxy-4-trans-decenoyl coenzyme A by a dehydration/hydration mechanism catalyzed by the multienzyme complex of fatty acid oxidation from Escherichia coli.
The mechanism of 3-hydroxyacyl-CoA epimerase (EC 5.1.2.3), which is associated with the multienzyme complex of fatty acid oxidation from Escherichia coli, was studied with D-3-hydroxy-4-trans-decenoyl-CoA as a substrate. The E. coli complex catalyzes the rapid and direct dehydration of D-3-hydroxy-4-trans-decenoyl-CoA to 2-trans,4-trans-decadienoyl-CoA, which is slowly hydrated to L-3-hydroxy-4-trans-decenoyl-CoA. A kinetic analysis of the epimerase and its partial reactions established that epimerization of 3-hydroxyacyl-CoAs occurs solely by a dehydration/hydration mechanism. The results of a substrate competition study with L-3-hydroxy-4-trans-decenoyl-CoA and its D-isomer, together with the conclusion from a sequence analysis of the large subunit of the E. coli complex (Yang, X.-Y., Schulz, H., Elzinga, M., and Yang, S.-Y. (1991) Biochemistry 30, 6788-6795), prompt the suggestion that a single active site is responsible for the dehydration of the D- and L-isomers of 3-hydroxyacyl-CoAs.
Smeland
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Department of Chemistry, City College, City University of New York, New York 10031.
Cuebas
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Schulz
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D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000201:enzymology*; D007536:Isomerism; D007700:Kinetics; D009097:Multienzyme Complexes / Q000378:metabolism*; D010084:Oxidation-Reduction; D019998:Racemases and Epimerases / Q000378:metabolism*
D009097:Multienzyme Complexes; D019998:Racemases and Epimerases; C029601:3-hydroxybutyryl-CoA epimerase