Hybrid Mn-Peroxidase from the Ligninolytic Fungus Panus tigrinus 8/18. Isolation, Substrate Specificity, and Catalytic Cycle

A. V. Lisov, A. A. Leontievsky^*, and L. A. Golovleva

Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, Pushchino 142290, Moscow Region, Russia; fax: (7-095) 956-3370; E-mail: leont@ibpm.pushchino.ru

^* To whom correspondence should be addressed.

Received December 3, 2002

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Increased manganese concentration during submerged cultivation of the ligninolytic white rot fungus Panus tigrinus 8/18 on N-limited mineral medium resulted in the induction of Mn-peroxidase and laccase. The Mn-peroxidase was purified with the purity factor RZ (A₄₀₆/A₂₈₀) = 4.3. The purified enzyme catalyzed H₂O₂-dependent oxidation of phenol oxidase substrates (aromatic amines, 2,2´-azinobis-(3-ethylbenzthiazolinesulfonic acid), hydroquinone, 2,6-dimethoxyphenol) without Mn²⁺, which is not typical for the usual Mn-peroxidases. Guaiacol and 2,4,6-trichlorophenol were not oxidized in the absence of Mn²⁺. Study of absorption spectra of the intermediates of the catalytic cycle revealed that this peroxidase is able to complete the redox cycle, reducing one-electron oxidized intermediate (Compound II) by Mn²⁺, as well as by an organic substrate (hydroquinone). This means that the enzyme is a “hybrid” Mn-peroxidase, different from the common Mn-peroxidases from ligninolytic fungi.

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KEY WORDS: Panus tigrinus, Mn-peroxidase, hybrid peroxidase, absorption spectra, catalytic cycle

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