Structural Studies with an Acidic Phospholipase A2 from B. jararacussu Complexed with p-bromophenacyl bromide Inhibitor at 1.85 Å Resolution

Agnes A. S. Takeda¹, Ângelo J. Magro¹, Silvana Marcussi², Lucas B. Silveira², Andreimar M. Soares², Marcos R. M. Fontes¹

1 Dep. de Física e Biofísica, Inst. de Biociências, UNESP - Botucatu, SP.  2 Dep. de Biotecnologia, UNAERP, Ribeirão Preto-SP.

Phospholipases A2 are small stable calcium-dependent enzymes that hydrolyze the sn-2acyl groups of phospholipids to liberate fatty acids and lysophospholipids. P-bromophenacyl bromide (BPB) also leads to the inactivation of PLA2s. These proteins have an active site located close to His48 residue and the enzyme can be inactivated by chemical modification of this residue with BPB. Recently, we have reported the isolation, biochemical and pharmacological characterization, and crystal structure of an acid PLA2 from B. jararacussu. Here, we described the preliminary structural studies with the complex BthA-I-BPB aiming to gaining insights about the inhibition mechanism of this protein. Crystals of complex BthA-I-BPB were obtained by the hanging drop vapor diffusion method using 0.2M magnesium chloride, 32\% PEG 4000 (w/v) and 0.1M Tris-HCl (pH 8.5). X-ray diffraction data were collected (LNLS, Campinas) and data set are 98.5 % complete at 1.85 Å resolution. BthA-I-BPB crystals belong to the space group P21. The crystals are not isomorphous with those of the native protein, suggesting the inhibitor binding to lead changes in the quaternary structure may have occurred.

Supported by FAPESP, LNLS and CNPq.

Correspondence to: agnestakeda@yahoo.com or fontes@ibb.unesp.br