Studies on .ALPHA.-amino acid ester hydrolase of Xanthomonas citri. I. Purification of .ALPHA.-amino acid ester hydrolase from Xanthomonas citri.

Abstract

α-Amino acid ester hydrolase, which can synthesize various kinds of semi-synthetic cephalosporins from 7-aminocephem compounds and α-amino acid esters, was purified to homogeneity from the cell-free extract of Xanthomonas citri IFO 3835 by ion-exchange chromatography and gel filtration. The purified enzyme migrated as a single band on disc gel electrophoresis and sedimented as a single symmetric peak on ultracentrifugation (s20, w = 11.8S). It showed a UV absorption maximum at 280 nm at pH 7.0 and had an isoelectric point at pH 7.8. Cysteine and cystine were not found in its molecule. Carbohydrate was not substantially detected. The molecular weight was estimated to be 270,000-280,000 by ultracentrifugation and gel filtration. The enzyme dissociated into subunits with an identical molecular weight of 72,000 in the presence of sodium dodecyl sulfate or guanidine · HCl.