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

摘要

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 (A_(406)/A_(280))=4.3.The purified enzyme catalyzed H_2O_2-dependent oxidation of phenol oxidase substrates (aromatic amines,2,2'-azinobis-(3-ethylbenzthiazolinesulfonic acid),hydroquinone,2,6-dimethoxyphenol)witout Mn~(2+),which is not typical for the usual Mn-peroxidases.Guaiacol and 2,4,6-trichlorophenol were not oxidized in the absence of Mn~(2+).Study of absorpton 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 Mn~(2+),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.