2jib | pdb_00002jib

File:2jib.jpg

X-RAY STRUCTURE OF OXALYL-COA DECARBOXYLASE IN COMPLEX WITH COENZYME-A

Overview

Despite more than five decades of extensive studies of thiamin diphosphate (ThDP) enzymes, there remain many uncertainties as to how these enzymes achieve their rate enhancements. Here, we present a clear picture of catalysis for the simple nonoxidative decarboxylase, oxalyl-coenzyme A (CoA) decarboxylase, based on crystallographic snapshots along the catalytic cycle and kinetic data on active site mutants. First, we provide crystallographic evidence that, upon binding of oxalyl-CoA, the C-terminal 13 residues fold over the substrate, aligning the substrate alpha-carbon for attack by the ThDP-C2 atom. The second structure presented shows a covalent reaction intermediate after decarboxylation, interpreted as being nonplanar. Finally, the structure of a product complex is presented. In accordance with mutagenesis data, no side chains of the enzyme are implied to directly participate in proton transfer except the glutamic acid (Glu-56), which promotes formation of the 1',4'-iminopyrimidine tautomer of ThDP needed for activation.

About this Structure

2JIB is a Single protein structure of sequence from Oxalobacter formigenes. Full crystallographic information is available from OCA.

Reference

Crystallographic snapshots of oxalyl-CoA decarboxylase give insights into catalysis by nonoxidative ThDP-dependent decarboxylases., Berthold CL, Toyota CG, Moussatche P, Wood MD, Leeper F, Richards NG, Lindqvist Y, Structure. 2007 Jul;15(7):853-61. PMID:17637344 Page seeded by OCA on Sun May 4 08:57:41 2008

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