Purification and Characterization of the β-Galactosidase of Aeromonas formicans

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Abstract
Rohlfing, S. R. (Western Reserve University, Cleveland, Ohio), and I. P. Crawford. Purification and characterization of the β-galactosidase of Aeromonas formicans. J. Bacteriol. 91:1085–1097. 1966.—The β-galactosidase of Aeromonas formicans was purified by diethylaminoethyl cellulose chromatography and gel filtration on Sephadex G-200. The properties of the enzyme molecule were compared with purified β-galactosidase from Escherichia coli. The sedimentation coefficients and electrophoretic mobilities of the two enzymes were not significantly different; the electrophoretic mobility of urea-produced subunits of the two enzymes was also similar. The stabilities of the two enzymes to denaturing agents provided measurable differences; E. coli β-galactosidase is relatively more heat-stable and more resistant to the action of urea. The amino acid compositions of the two proteins revealed significant differences in several amino acids, particularly alanine, arginine, glycine, and leucine. The comparisons cited suggest that A. formicans and E. coli are not completely unrelated, for their β-galactosidases show considerable structural similarity. Images

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