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 protein 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 magnesium chloride or 1 M lithium chloride. Crystals of the first form belong to the space group C222(1) and diffract to 3.0 Angstrom resolution, whereas crystals of the second form belong to the space group P2(1)2(1)2 and diffract to 2.3 Angstrom resolution. Initial screening for heavy-atom derivatives on form IT crystals, has led to a well substituted Hg derivative.