4iy7

Publication Abstract from PubMed

Numerous enzymes, such as the pyridoxal 5'-phosphate (PLP)-dependent enzymes, require cofactors for their activities. Using X-ray crystallography, structural snapshots of the L-serine dehydratase catalytic reaction of a bacterial PLP-dependent enzyme were determined. In the structures, the dihedral angle between the pyridine ring and the Schiff-base linkage of PLP varied from 18 degrees to 52 degrees . It is proposed that the organic cofactor PLP directly catalyzes reactions by active conformational changes, and the novel catalytic mechanism involving the PLP cofactor was confirmed by high-level quantum-mechanical calculations. The conformational change was essential for nucleophilic attack of the substrate on PLP, for concerted proton transfer from the substrate to the protein and for directing carbanion formation of the substrate. Over the whole catalytic cycle, the organic cofactor catalyzes a series of reactions, like the enzyme. The conformational change of the PLP cofactor in catalysis serves as a starting point for identifying the previously unknown catalytic roles of organic cofactors.

PLP undergoes conformational changes during the course of an enzymatic reaction.,Ngo HP, Cerqueira NM, Kim JK, Hong MK, Fernandes PA, Ramos MJ, Kang LW Acta Crystallogr D Biol Crystallogr. 2014 Feb;70(Pt 2):596-606. doi:, 10.1107/S1399004713031283. Epub 2014 Jan 31. PMID:24531493^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.