A novel enzyme, maltose 1-epimerase from Lactobacillus brevis IFO 3345.

A novel enzyme, maltose 1-epimerase (MER), that catalyzes the interconversion of alpha and beta anomers of maltose was found in a cell-free extract of Lactobacillus brevis IFO 3345, and MER was purified to homogeneity from the crude extract. The M(r) of the enzyme was estimated to be 43,000 and 45,000 by HPLC gel filtration and SDS-PAGE, respectively. It showed optimum activity at pH 6.5-7.0. This novel enzyme catalyzed the conversion of beta-maltose more effectively than disaccharides such as alpha-lactose and beta-cellobiose, whereas the relative velocities for beta- and alpha-D-glucose were about one forth of that for beta-maltose.