2c3c
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2.01 ANGSTROM X-RAY CRYSTAL STRUCTURE OF A MIXED DISULFIDE BETWEEN COENZYME M AND NADPH-DEPENDENT OXIDOREDUCTASE 2-KETOPROPYL COENZYME M CARBOXYLASE
OverviewOverview
The structure of the mixed, enzyme-cofactor disulfide intermediate of, ketopropyl-coenzyme M oxidoreductase/carboxylase has been determined by, X-ray diffraction methods. Ketopropyl-coenzyme M, oxidoreductase/carboxylase belongs to a family of pyridine, nucleotide-containing flavin-dependent disulfide oxidoreductases, which, couple the transfer of hydride derived from the NADPH to the reduction of, protein cysteine disulfide. Ketopropyl-coenzyme M, oxidoreductase/carboxylase, a unique member of this enzyme class, catalyzes thioether bond cleavage of the substrate, 2-ketopropyl-coenzyme, M, and carboxylation of what is thought to be an enzyme-stabilized, enolacetone intermediate. The mixed disulfide of 2-ketopropyl-coenzyme M, oxidoreductase/carboxylase was captured through crystallization of the, enzyme with the physiological products of the reaction, acetoacetate, coenzyme M, and NADP, and reduction of the crystals with dithiothreitol, just prior to data collection. Density in the active-site environment, consistent with acetone, the product of reductive decarboxylation of, acetoacetate, was revealed in this structure in addition to a well-defined, hydrophobic pocket or channel that could be involved in the access for, carbon dioxide. The analysis of this structure and that of a, coenzyme-M-bound form provides insights into the stabilization of, intermediates, substrate carboxylation, and product release.
About this StructureAbout this Structure
2C3C is a Single protein structure of sequence from Xanthobacter autotrophicus with COM, FAD, NAP and ACN as ligands. Active as 2-oxopropyl-CoM reductase (carboxylating), with EC number 1.8.1.5 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
Mechanistic implications of the structure of the mixed-disulfide intermediate of the disulfide oxidoreductase, 2-ketopropyl-coenzyme M oxidoreductase/carboxylase., Pandey AS, Nocek B, Clark DD, Ensign SA, Peters JW, Biochemistry. 2006 Jan 10;45(1):113-20. PMID:16388586
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