Crystallization and preliminary X-ray analysis of a new L-aminopeptidase-D-amidase/D-esterase activated by a Gly-Ser peptide bond hydrolysis

Ochrobactrum anthropi possesses an L-aminopeptidase (DmpA) also able to act as a D-amidase/D-esterase. DmpA (40 kDa) is activated by auto-catalyzed pr otein splicing liberating an alpha-amino group presumably used as a general base in the catalytic mechanism. Two crystal forms were obtained at 294 K in 13-16% PEG 2000 mono-methylether at pH 9.0, adding either 0.2 M magnesiu m chloride or 1 M lithium chloride. Crystals of the first form belong to th e space group C222(1) and diffract to 3.0 Angstrom resolution, whereas crys tals of the second form belong to the space group P2(1)2(1)2 and diffract t o 2.3 Angstrom resolution. Initial screening for heavy-atom derivatives on form IT crystals, has led to a well substituted Hg derivative.