Reduction of plastocyanin with O₂⁻ and superoxide dismutase-dependent oxidation of plastocyanin by H₂O₂

Takahashi, Masa-aki; Kono, Yasuhisa; Asada, Kozi

Reduction of plastocyanin with O₂⁻ and superoxide dismutase-dependent oxidation of plastocyanin by H₂O₂

1980

Takahashi, Masa-aki | Kono, Yasuhisa | Asada, Kozi

Type I copper proteins, plastocyanin and rice blue protein, were reduced with O ₂⁻. The reduction rate constants of plastocyanins from several sources with O ₂⁻ are about 10 ⁶ m ⁻¹ sec ⁻¹ (1.0 × 10 ⁶ m ⁻¹ sec ⁻¹ for spinach and kidney bean plastocyanins and 6.7 × 10 ⁵ m ⁻¹sec ⁻¹ for Japanese radish plastocyanin) at pH 7.8 at 25°C and not significantly different from that observed for rice blue protein (7.3 × 10 ⁵ m ⁻¹sec ⁻¹). Reduced plastocyanin was oxidized by H ₂O ₂ through the peroxidase-like reaction of Cu,Zn-superoxide dismutase.

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