Immobilization of b-D-galactosidase from Lactobacillus bulgaricus on polyacrylamide in the presence of protective agents and properties of the immobilized enzyme.

ABSTRACT

b-D-Galactosidase (EC 3.2.1.23) from Lactobacillus bulgaricus (1373) was immobilized in a Polyacrylamide gel lattice in the presence of dithiothreitol, glutathione, cysteine, bovine serum albumin, casein, lactose and glucono-δ-lactone. Cysteine, bovine serum albumin, and lactose were found very effective in preserving the activity. With cysteine, bovine serum albumin and lactose, the activity yields were 61, 60 and 66% respectively, as compared to 31% without protective agents. The yield improved upto 85% when all the three protective agents, cysteine, bovine serum albumin and lactose were added during immobilization. The addition of protective agents did not have any effect on optimum pH, optimum temperature, kinetic constants and pH stability when compared with β-galactosidase immobilized without the use of protective agents; however the heat and storage stabilities were found to increase.