Identification of Catalytically Active Groups of Penicillium canescens F-436 beta-Galactosidase

O. S. Korneeva^*, N. A. Zherebtsov, and I. V. Cheryomushkina

Voronezh State Technological Academy, pr. Revolyutsii 19, Voronezh, 394017 Russia; fax: (0732) 55-4267; E-mail: post@vgta.vrn.ru

^* To whom correspondence should be addressed.

Received May 26, 2000; Revision received October 26, 2000

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The functional groups of Penicillium canescens F-436 beta-galactosidase have been identified. The pK values and heats of ionization of these groups and photoinactivation of the enzyme with methylene blue indicate that the active site contains carboxyl and imidazole groups. A mechanism for the participation of these groups in the cleavage of the glycoside bond in lactose is proposed.

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KEY WORDS: beta-galactosidase, hydrolysis of lactose, photoinactivation, mechanism of action, Penicillium canescens

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