1une
From Proteopedia
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CARBOXYLIC ESTER HYDROLASE, 1.5 ANGSTROM ORTHORHOMBIC FORM OF THE BOVINE RECOMBINANT PLA2
Overview
The X-ray structure of recombinant bovine pancreatic phospholipase A2, (PLA2), which specifically catalyzes the cleavage of the sn-2 acylester, bond of phospholipids, has been refined at 1.5 A resolution. The crystal, belongs to the space group P212121 with unit-cell parameters a = 47.12, b, = 64.59 and c = 38.14 A similar to the native enzyme reported previously, by Dijkstra et al. [J. Mol. Biol. (1981), 147, 97-123]. The refinement, converged to an R value of 18.4% (Rfree = 22.8%) for 16 374 reflections, between 10.0 and 1.5 A resolution. The surface-loop residues (60-70) are, ordered in the present orthorhombic recombinant enzyme, but disordered in, the trigonal recombinant enzyme. The active-site residues, His48, Asp99, and the catalytic water superimpose well with the trigonal form. Besides, the catalytic water which is hydrogen bonded to His48, it is often seen, that there is a second water attached to the same N atom of His48 and, simultaneously hydrogen bonded to the O atom of Asp49. It is thought that, the second water facilitates the tautomerism of His48 for enzyme, catalysis. The catalytic water is also hydrogen bonded to the equatorial, water coordinated to the calcium ion. In addition to the equatorial water, there is also an axial calcium water and the additional structural water., These five common water molecules are hydrogen bonded to the additional 16, water molecules in the present orthorhombic structure which may further, enhance the structural integrity of the active site. Besides the protein, and one calcium ion, a total of 134 water molecules were located in the, present high-resolution refinement.
About this Structure
1UNE is a Single protein structure of sequence from Bos taurus with CA as ligand. Active as Phospholipase A(2), with EC number 3.1.1.4 Full crystallographic information is available from OCA.
Reference
High-resolution refinement of orthorhombic bovine pancreatic phospholipase A2., Sekar K, Sundaralingam M, Acta Crystallogr D Biol Crystallogr. 1999 Jan;55(Pt 1):46-50. Epub 1999, Jan 1. PMID:10089393
Page seeded by OCA on Wed Nov 21 04:15:33 2007
