Purification and properties of two lactose hydrolases from Trichosporon cutaneum

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Abstract
Two enzymes that hydrolysed lactose were purified essentially to homogeneity from cell extracts of the oleaginous yeast Trichosporon cutaneum. One enzyme of Mr 120 000 had properties typical of a .beta.-galactosidase (EC 3.21.1.23). It hydrolysed lactose, lactulose and nitrophenyl-.beta.-D-galactosides. The enzyme required K+ or Rb+ for activity, and other monovalent cations tested were not effective. Enzyme activity was abolished by EDTA and stimulated by Mg2+, Mn2+ and Ca2+. The .beta. galactosidase was induced by lactose, galactose, lactulose and lactobionic acid. The other enzyme, a .beta.-glycosidase (EC 3.2.1.21) of Mr 52 000 showed no ionic requirements and it hydrolysed lactose, nitrophenyl-.beta.-D-galactosides, 4-nitrophenyl-.beta.-D-glucoside, celloboise, laminaribiose, laminaritriose and sophorose, but not gentiobiose, 4-nitrophenyl-.beta.-D-mannoside or sucrose. This enzyme was induced by lactose, galactose and lactulose, and also by celloboise.