Kinetics and properties of partially purified yeast B galactosidase produced in salted whey

ABSTRACT

The B-galactosidase enzyme of Kluyveromyces lactis NRRL-1118 grown in salted whey medium was obtained by solvent extraction and also by sonication of the cell for different periods. Best results were obtained by interrupted sonication for 20 min with cooling of the cells. The enzyme was purified 37 times by fractional precipitation using acetone and repeated centrifugation. The partially purified enzyme has optimum pH between 6.5-7.0 and Km 1.18 mM for ONPG as substrate. The enzyme was heat labile and exhibited maximum activity at 40 degree C. Notable activation of the enzyme was detected with manganese ion whereas little or no effect was observed for several cations