Immobilization of Thermostable α-Galactosidase from Pycnoporus cinnabarinus on Chitin and Some Properties of the Immobilized Enzyme

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α-Galactosidase (EC 3.2.1.22) from Pycnoporus cinnabarinus was well immobilized on colloidal chitin with glutaraldehyde. The immobilized α-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 with shaking at pH 5.0 and at 25℃ for 1 h. The immobilized enzyme had the optimum pH at 4.5-5.0 and the optimum temperature at 75℃, and was stable between pH 3 and 9 (for 2 h at 37℃) and below 80℃(for 15 min at pH 5.0). The enzyme was strongly inhibited by AG^+, Hg^<++>, galactose, and melibiose, and its K_m value for the hydrolysis of p-nitrophenyl α-D-galactopyranoside was 0.32 mM. These enzymatic properties of the immobilized α-galactosidase were similar to those of native enzym. The immobilized enzyme retained about 90% of the initial activity even after being used for 20 times.
1985-08-25