Crystallization and X-ray diffraction analysis of ornithine cyclodeaminase from Pseudomonas putida.

Ornithine cyclodeaminase (OCD) is a member of the μ-crystallin protein family, the biological activity of which is the conversion of L-ornithine to L-proline and ammonia. In order to elucidate the functional groups of this enzyme that arc involved in catalysis. the crystallization of OCL) from Pseudomonas Putida was undertaken. Using microbatch-under-oil screening at the high-throughput crystallization laboratory (HTC) at the Hauptman-Woodward Medical Research Institute Inc. (HWI Buffalo, NY, USA), numerous crystallization conditions were rapidly identified. Several conditions could he reproduced on a larger scale as vapor-diffusion experiments in-house. The best diffraction-quality crystals were obtained front solutions of 40%(v/v) 2-methyl-2,4-pentanediol buffered at pH 6.0 with 0.1 M MES and diffracted X-rays to 1.68 Å resolution. Crystals belonged to space group P2₁2₁2₁, with unit-cell parameters a = 70.0, b = 78.3, c = 119.4 Å. The V_M was 2.1 ų Da^-1. corresponding to 42% solvent, which is consistent with two 38.5 kDa molecules per asymmetric unit. The structure determination is under way using experimental phasing methods. [ABSTRACT FROM AUTHOR]