1gh4

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spinqualitylabelsall models 1gh4, resolution 1.9Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Structure of the triple mutant (K56M, K120M, K121M) of phospholipase A2

Overview

Phospholipase A(2) catalyses hydrolysis of the ester bond at the C2, position of 3-sn-phosphoglycerides. Here we report the 1.9A resolution, crystal structure of the triple mutant K56,120,121M of bovine pancreatic, phospholipase A(2). The structure was solved by molecular replacement, method using the orthorhombic form of the recombinant phospholipase A(2)., The final protein model contains all the 123 amino acid residues, two, calcium ions, 125 water molecules and one 2-methyl-2-4-pentanediol, molecule. The model has been refined to a crystallographic R-factor of, 19.6% (R(free) of 25.9%) for all data between 14.2A and 1.9A. The residues, 62-66, which are in a surface loop, are always disordered in the, structures of bovine pancreatic phospholipase A(2) and its mutants. It is, interesting to note that the residues 62-66 in the present structure is, ordered and the conformation varies substantially from those in the, previously published structures of this enzyme. An unexpected and, interesting observation in the present structure is that, in addition to, the functionally important calcium ion in the active site, one more, calcium ion is found near the N terminus. Detailed structural analyses, suggest that binding of the second calcium ion could be responsible for, the conformational change and the ordering of the surface loop., Furthermore, the results suggest a structural reciprocity between the, k(cat)(*) allosteric site and surface loop at the i-face, which represents, a newly identified structural property of secreted phospholipase A(2).

About this Structure

1GH4 is a Single protein structure of sequence from Bos taurus with CA and MPD as ligands. Active as Phospholipase A(2), with EC number 3.1.1.4 Full crystallographic information is available from OCA.

Reference

Observation of additional calcium ion in the crystal structure of the triple mutant K56,120,121M of bovine pancreatic phospholipase A2., Rajakannan V, Yogavel M, Poi MJ, Jeyaprakash AA, Jeyakanthan J, Velmurugan D, Tsai MD, Sekar K, J Mol Biol. 2002 Dec 6;324(4):755-62. PMID:12460575

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