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 -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 C222₁ and diffract to 3.0 Å resolution, whereas crystals of the second form belong to the space group and diffract to 2.3 Å resolution. Initial screening for heavy-atom derivatives on form II crystals, has led to a well substituted Hg derivative.