title: The 2-A crystal structure of 6-oxo camphor hydrolase. New structural diversity in the crotonase superfamily.
abstract: 6-Oxo camphor hydrolase (OCH) is an enzyme of the crotonase superfamily that catalyzes carbon-carbon bond cleavage in bicyclic beta-diketones via a retro-Claisen reaction (Grogan, G., Roberts, G. A., Bougioukou, D., Turner, N. J., and Flitsch, S. L. (2001) J. Biol. Chem. 276, 12565-12572). The native structure of OCH has been solved at 2.0-A resolution with selenomethionine multiple wave anomalous dispersion and refined to a final R(free) of 19.0. The structure of OCH consists of a dimer of trimers that resembles the "parent" enzyme of the superfamily, enoyl-CoA hydratase. In contrast to enoyl-CoA hydratase, however, two octahedrally coordinated sodium atoms are found at the 3-fold axis of the hexamer of OCH, and the C-terminal helix of OCH does not form a discrete domain. Models of the substrate, 6-oxo camphor, and a proposed enolate intermediate in the putative active site suggest possible mechanistic roles for Glu-244, Asp-154, His-122, His-45, and His-145.
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York, North Yorkshire YO10 5YW, United Kingdom.
authors.forename: Jean L
authors.initials: JL
authors.lastname: Whittingham
authors.forename: Johan P
authors.initials: JP
authors.lastname: Turkenburg
authors.forename: Chandra S
authors.initials: CS
authors.lastname: Verma
authors.forename: Martin A
authors.initials: MA
authors.lastname: Walsh
authors.forename: Gideon
authors.initials: G
authors.lastname: Grogan
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D017931:DNA Primers; D004746:Enoyl-CoA Hydratase / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D004746:Enoyl-CoA Hydratase