Structure, kinetics, molecular and redox properties of a cytosolic and developmentally regulated fungal catalase-peroxidase.
Arch Biochem Biophys
; 640: 17-26, 2018 02 15.
Article
em En
| MEDLINE
| ID: mdl-29305053
CAT-2, a cytosolic catalase-peroxidase (CP) from Neurospora crassa, which is induced during asexual spore formation, was heterologously expressed and characterized. CAT-2 had the Met-Tyr-Trp (M-Y-W) adduct required for catalase activity. Its KM for H2O2 was micromolar for peroxidase and millimolar for catalase activity. A Em = -158 mV reduction potential value was obtained and the Soret band shift suggested a mixture of low and high spin ferric iron. CAT-2 EPR spectrum at 10 K indicated an axial and a rhombic component. With peroxyacetic acid (PAA), formation of Compound I* was observed with EPR. CAT-2 homodimer crystallographic structure contained two K+ ions; Glu107 residues were displaced to bind them. CAT-2 showed the essential amino acid residues for activity in similar positions to other CPs. CAT-2 Arg426 is oriented towards the M-Y-W adduct, interacting with the deprotonated Tyr238 hydroxyl group. A perhydroxy modification of the indole nitrogen of Trp90 was oriented toward the catalytic His91. In contrast to cytochrome c peroxidase and ascorbate peroxidase, the catalase-peroxidase heme propionates are not exposed to the solvent. Together with other N. crassa enzymes that utilize H2O2 as a substrate, CAT-2 has many tryptophan and proline residues at its surface, probably related to H2O2 selection in water.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peroxidases
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Catalase
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Citosol
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Peróxido de Hidrogênio
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Neurospora crassa
Idioma:
En
Revista:
Arch Biochem Biophys
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
México
País de publicação:
Estados Unidos