Stereoselectivity of enoyl-CoA hydratase results from preferential activation of one of two bound substrate conformers.
Enoyl-CoA hydratase catalyzes the hydration of trans-2-crotonyl-CoA to 3(S)- and 3(R)-hydroxybutyryl-CoA with a stereoselectivity (3(S)/3(R)) of 400,000 to 1. Importantly, Raman spectroscopy reveals that both the s-cis and s-trans conformers of the substrate analog hexadienoyl-CoA are bound to the enzyme, but that only the s-cis conformer is polarized. This selective polarization is an example of ground state strain, indicating the existence of catalytically relevant ground state destabilization arising from the selective complementarity of the enzyme toward the transition state rather than the ground state. Consequently, the stereoselectivity of the enzyme-catalyzed reaction results from the selective activation of one of two bound substrate conformers rather than from selective binding of a single conformer. These findings have important implications for inhibitor design and the role of ground state interactions in enzyme catalysis.
Bell
Alasdair F
AF
Department of Chemistry, Center for Structural Biology, SUNY at Stony Brook, Stony Brook, NY 11794, USA.
Feng
Yuguo
Y
Hofstein
Hilary A
HA
Parikh
Sapan
S
Wu
Jiaquan
J
Rudolph
Michael J
MJ
Kisker
Caroline
C
Whitty
Adrian
A
Tonge
Peter J
PJ
D000214:Acyl Coenzyme A / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D004746:Enoyl-CoA Hydratase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000737:chemistry; D015394:Molecular Structure; D009154:Mutation; D051381:Rats; D011994:Recombinant Proteins; D013059:Spectrum Analysis, Raman; D013237:Stereoisomerism; D013379:Substrate Specificity
D000214:Acyl Coenzyme A; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; C417225:hexadienoyl-coenzyme A; D004746:Enoyl-CoA Hydratase