1dss
From Proteopedia
STRUCTURE OF ACTIVE-SITE CARBOXYMETHYLATED D-GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE FROM PALINURUS VERSICOLOR
Overview
The structure of active site carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase from Palinurus versicolor was determined in the presence of coenzyme NAD+ at 1.88 A resolution with a final R-factor of 0.175. The structure refinement was carried out on the basis of the structure of holo-GAPDH at 2.0 A resolution using the program XPLOR. The carboxymethyl group connected to Cys149 is stabilized by a hydrogen bond between its OZ1 and Cys149N, and charge interaction between the carboxyl group and the nicotinamide moiety. The modification of Cys149 induced conformational changes in the active site, in particular, the site of sulphate ion 501 (the proposed attacking inorganic phosphate ion in catalysis), and segment 208-218 nearby. Extensive hydrogen-bonding interactions occur in the active site, which contribute to the higher stability of the modified enzyme. The modification of the active site did not affect the conformation of GAPDH elsewhere, including the subunit interfaces. The structures of the green and red subunits in the asymmetric unit are nearly identical, suggesting that the half-site reactivity of this enzyme is from ligand-induced rather than pre-existing asymmetry. It is proposed that the carboxymethyl group takes the place of the acyl group of the reaction intermediate, and the catalytic mechanism of this enzyme is discussed in the light of a comparison of the structures of the native and the carboxymethylated GAPDH.
About this Structure
1DSS is a Single protein structure of sequence from Palinurus versicolor. Full crystallographic information is available from OCA.
Reference
Structure of active site carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase from Palinurus versicolor., Song SY, Xu YB, Lin ZJ, Tsou CL, J Mol Biol. 1999 Apr 9;287(4):719-25. PMID:10191140 Page seeded by OCA on Fri May 2 14:13:47 2008
