Immobilization of thermostable alpha galactosidase from pycnoporus cinnabarinus on chitin and some properties of the immobilized enzyme
Mitsutomi, M.; Uchida, Y.; Ohtakara, A.
Journal of Fermentation Technology 63(4): 325-330
.alpha.-Galactosidase (EC 188.8.131.52) from Pycnoporus cinnabarinus was well immobilized on colloidal chitin with glutaraldehyde. The immobilized .alpha.-galactosidase was prepared with a high yield of about 85% by incubating a mixture of 50 units of the enzyme and 0.2 g of colloidal chitin was shaking at ph 5.0 and at 25.degree. C for 1 h. The immobilized enzyme had the optimum pH at 4.5-5.0 and the optimum temperature at 75.degree. C, and was stable between pH 3 and 9 (for 2 h at 37.degree. C) and below 80.degree. C (for 15 min at pH 5.0). The enzyme was strongly inhibited by Ag+, Hg++, galactose, and melibiose, and its Km value for the hydrolysis of p-nitrophenyl .alpha.-D-galactopyranoside was 0.32 mM. These enzymatic properties of the immobilized .alpha.-galactosidase were similar to those of native enzyme. The immobilized enzyme retained about 90% of the initial activity even after being used for 20 times.