2ji9: Difference between revisions

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.

2JI9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Oxalobacter_formigenes Oxalobacter formigenes] with MG, TPW, ADP and B3P as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Oxalyl-CoA_decarboxylase Oxalyl-CoA decarboxylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.1.8 4.1.1.8] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2JI9 OCA].  

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