Open AccessImproved X‐ray diffraction from Bacillus megaterium penicillin G acylase crystals through long cryosoaking dehydration
Author(s) -
Rojviriya Catleya,
Pratumrat Thunyaluck,
Saper Mark A.,
Yuvaniyama Jirundon
Publication year - 2011
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309111040462
Subject(s) - bacillus megaterium , mosaicity , penicillin amidase , monoclinic crystal system , crystallization , penicillin , crystallography , chemistry , dehydration , crystal structure , escherichia coli , x ray crystallography , bacteria , diffraction , biochemistry , biology , antibiotics , organic chemistry , physics , genetics , gene , optics
Penicillin G acylase from Bacillus megaterium ( Bm PGA) is currently used in the pharmaceutical industry as an alternative to PGA from Escherichia coli ( Ec PGA) for the hydrolysis of penicillin G to produce 6‐aminopenicillanic acid (6‐APA), a penam nucleus for semisynthetic penicillins. Despite the significant differences in amino‐acid sequence between PGAs from Gram‐positive and Gram‐negative bacteria, a representative PGA structure of Gram‐positive origin has never been reported. In this study, crystallization and diffraction studies of Bm PGA are described. Poor diffraction patterns with blurred spots at higher resolution were typical for Bm PGA crystals cryocooled after a brief immersion in cryoprotectant solution. Overnight soaking in the same cryo‐solution substantially improved both the mosaicity and resolution limit through the establishment of a new crystal‐packing equilibrium. A crystal of Bm PGA diffracted X‐rays to 2.20 Å resolution and belonged to the monoclinic space group P 2 1 with one molecule of Bm PGA in the asymmetric unit.