1kh3
From Proteopedia
Crystal Structure of Thermus thermophilus HB8 Argininosuccinate Synthetase in complex with inhibitor
Overview
Argininosuccinate synthetase reversibly catalyzes the ATP-dependent condensation of a citrulline with an aspartate to give argininosuccinate. The structures of the enzyme from Thermus thermophilus HB8 complexed with intact ATP and substrates (citrulline and aspartate) and with AMP and product (argininosuccinate) have been determined at 2.1- and 2.0-A resolution, respectively. The enzyme does not show the ATP-induced domain rotation observed in the enzyme from Escherichia coli. In the enzyme-substrate complex, the reaction sites of ATP and the bound substrates are adjacent and are sufficiently close for the reaction to proceed without the large conformational change at the domain level. The mobility of the triphosphate group in ATP and the side chain of citrulline play an important role in the catalytic action. The protonated amino group of the bound aspartate interacts with the alpha-phosphate of ATP and the ureido group of citrulline, thus stimulating the adenylation of citrulline. The enzyme-product complex explains how the citrullyl-AMP intermediate is bound to the active site. The stereochemistry of the catalysis of the enzyme is clarified on the basis of the structures of tAsS (argininosuccinate synthetase from T. thermophilus HB8) complexes.
About this Structure
1KH3 is a Single protein structure of sequence from Thermus thermophilus. Full crystallographic information is available from OCA.
Reference
Structures of argininosuccinate synthetase in enzyme-ATP substrates and enzyme-AMP product forms: stereochemistry of the catalytic reaction., Goto M, Omi R, Miyahara I, Sugahara M, Hirotsu K, J Biol Chem. 2003 Jun 20;278(25):22964-71. Epub 2003 Apr 8. PMID:12684518 Page seeded by OCA on Fri May 2 22:44:22 2008
