Purification and properties of an inducible beta-galactosidase isolated from the yeast Kluyveromyces lactis

Abstract
.beta.-Galactosidase (EC 3.2.1.32) was purified 80-fold from the yeast K. lactis induced for this enzyme by growth on lactose. When the purified enzyme was subjected to electrophoresis on an acrylamide gel in the presence of sodium dodecyl sulfate, 1 protein with an apparent MW of 135,000 was observed. The enzyme has a sedimentation coefficient of 9.6S. This .beta.-galactosidase and the one from Escherichia coli are not antigenically related. Maximal enzyme activity requires Na+ and Mn2+ and a reducing agent. .beta.-Galactosidase has Km values of 12-17 and 1.6 mM for lactose and o-nitrophenyl-.beta.-D-galactoside, respectively. The hydrolase and transgalactosylase activities of the enzyme are similar to those of E. coli .beta.-galactosidase.