[Isolation and characterization of beta-D-galactosidase from gastric juice].

A method for beta-D-galactosidase isolation from cattle gastric juice has been developed. Gastric juice mucus was removed by and addition of equimolar amounts of Na2HPO4 and CaCl2. The removal of proteases and other proteins was achieved by the treatment with resins KB-51X2 and AN-22. The resulting preparation had specific activity of 0.14 units per mg of protein. Gel filtration on Sepharose 4B led to an increase of specific activity of the preparation up to 0,4 units per mg of protein. Some properties of the beta-D-galactosidase obtained were compared to relation of lactose and o-nitrophenyl-beta-D-galactoside (pH optima, temperature optimym and thermostability).