1nsq

Publication Abstract from PubMed

Nucleoside diphosphate kinase (NDP kinase) has a ping-pong mechanism with a phosphohistidine intermediate. Crystals of the enzymes from Dictyostelium discoideum and from Drosophila melanogaster were treated with phosphoramidate, and their X-ray structures were determined at 2.1 and 2.2 A resolution, respectively. The atomic models, refined to R factors below 20%, show no conformation change relative to the free proteins. In both enzymes, the active site histidine was phosphorylated on N delta, and it was the only site of phosphorylation. The phosphate group interacts with the hydroxyl group of Tyr56 and with protein-bound water molecules. Its environment is compared with that of phosphohistidines in succinyl-CoA synthetase and in phosphocarrier proteins. The X-ray structures of phosphorylated NDP kinase and of previously determined complexes with nucleoside diphosphates provide a basis for modeling the Michaelis complex with a nucleoside triphosphate, that of the phosphorylated protein with a nucleoside diphosphate, and the transition state of the phosphate transfer reaction in which the gamma-phosphate is pentacoordinated.

Mechanism of phosphate transfer by nucleoside diphosphate kinase: X-ray structures of the phosphohistidine intermediate of the enzymes from Drosophila and Dictyostelium.,Morera S, Chiadmi M, LeBras G, Lascu I, Janin J Biochemistry. 1995 Sep 5;34(35):11062-70. PMID:7669763^[4]

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