Third calcium ion found in an inhibitor-bound phospholipase A2

Sekar, K and Gayathri, D and Velmurugan, D and Jeyakanthan, J and Yamane, T and Poi, MJ and Tsai, MD (2006) Third calcium ion found in an inhibitor-bound phospholipase A2. In: Acta Crystallographica Section D-Biological Crystallography, 62 (4). 392 -397.

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Abstract

The lipolytic enzyme phospholipase A(2) plays a crucial role in lipid metabolism and catalyzes hydrolysis of the fatty-acid ester bond at the sn-2 position of phospholipids. Here, the crystal structure (1.7 angstrom resolution) of the triple mutant (K53,56,121M) of bovine pancreatic phospholipase A2 complexed with an organic molecule, p-methoxybenzoic acid (anisic acid), is reported. Residues 60-70 (the surface-loop residues) are ordered and adopt conformations which are different from those normally found in structures in which a second calcium ion is present. It is interesting to note that for the first time a third calcium ion has been identified. In addition, four Tris (2-amino-2-hydroxymethyl-1,3-propanediol) molecules were located. It is believed that one of the Tris molecules plays a role in clamping the third calcium ion and that another is involved in controlling the dynamics of the surface loop through hydrogen bonds.

Item Type:	Journal Article
Publication:	Acta Crystallographica Section D-Biological Crystallography
Publisher:	International Union of Crystallography
Additional Information:	Copyright of this article belongs to International Union of Crystallography.
Keywords:	phospholipase A2;anisic acid.
Department/Centre:	Division of Interdisciplinary Sciences > Supercomputer Education & Research Centre
Date Deposited:	13 Apr 2009 05:57
Last Modified:	19 Sep 2010 04:59
URI:	http://eprints.iisc.ac.in/id/eprint/17906

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