PURIFICATION AND CHARACTERIZATION OF β-GALACTOSIDASE FROM MUCOR PUSILLUS

The β-galactosidase from Mucor pusillus was purified by acetone precipitation, gel filtration and ion-exchange chromatography. Its molecular weight was 129 kDa on SDS PAGE, and its pI was 4.55. Optimum activity was observed at pH 4 and at 65C. Thermal denaturation at temperatures above 60C was essentially first order with an activation energy of 26.4 KJ/mole. Activity was not affected by metal ions or EDTA but was inhibited by galactose and galactono 1–4 lactone. The K_m for lactose at 37C was 22 mM. The enzyme was devoid of cysteine/cystine and stained positive for carbohydrate. Overall the enzyme is similar in structural and kinetic properties to the β-galactosidase from Aspergillus niger.