Anomerization and hydrolysis of lactose by beta-galactosidase from Saccharomyces lactis.

Beta-Galactosidase from Saccharomyces lactis was found to be able to catalyze both the anomerization of alpha-lactose and the hydrolysis of beta-lactose; the rate of hydrolysis appeared to be four times higher with a 1:1 mixture of alpha and beta lactose than with a freshly prepared solution of alpha-lactose. The enzyme was also found to be unable to hydrolyze alpha-lactose. Thus, it appears that beta-galactosidase from S. lactis has its hydrolytic activity on lactose adapted only to the naturally more abundant beta-lactose.