[Characteristics of a beta-galactosidase substance obtained by an ultrafiltration method].

: The ultrafiltration method with application of Vladipor membranes YAM-300 has been used to obtain 8.9 times purified preparation of beta-D-galactosidase (EC 3.2.1.23) from the Escherichia coli lysate. The preparation activity is 43,400 u/g, specific activity--167.57 u/mg of protein. The preparation includes 25.9% of protein and does not possess the collateral proteolytic activity. The results of the ultraconcentrate isofocusing in the borate-polyol system within the pH range of 4.5-9.5 and electrophoresis in polyacrylamide gel testify to the presence of five basic protein fractions, one of which includes 57 +/- 2% of protein with the beta-galactosidase activity. This fraction is homogeneous, its isoelectric point corresponds to pH 7.8.