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- Title
A Novel Mixed Valence Form of Rhus vernicifera Laccase and Its Reaction with Dioxygen to Give a Peroxide Intermediate Bound to the Trinuclear Center1.
- Authors
Zoppellaro, Giorgio; Sakurai, Takeshi; Huang, Hong-wei
- Abstract
Rhus vernicifera laccase, in a novel mixed valence state [TloxT23red: type 1 Cu as Cu(II), and type 2 and 3 Cus as Cu(I)], was formed by reacting Cu(I) on the type 2 Cu-depleted laccase [T1oxT3red: type 1 Cu as Cu(II) and type 3 Cus as Cu(I)] under argon. Contrary to T1oxT3red, T1oxT23red was highly reactive with dioxygen, and gave the three transient bands at 340, 475, and 680 nm due to the two-electron reduced form of dioxygen [charge transfer bands from peroxide to Cu(II)]. The first order decays were highly dependent on pH, which led to the successful detection of the intermediate for ca. 2 h at pH 7.5. Another mixed valence derivative, T12oxT3red [type 1 and type 2 Cus as Cu(II), and type 3 Cus as Cu(I)] prepared through the action of Cu(II) on T1oxT3red was not reactive with dioxygen, but showed high enzyme activity as to the oxidation of N,N-dimethyl-p-phenylenediamine. The whole reaction mechanism of the reduction of dioxygen by laccase was proposed based on the present results together with data for the former detection and characterization of the three-electron reduced form of dioxygen [Huang, H. et al. (1999) J. BioL Chem. 274,46, 32718–32724].
- Subjects
TOXICODENDRON vernicifluum; DIOXYGENASES; OXIDOREDUCTASES; HYDROGEN-ion concentration; LACCASE
- Publication
Journal of Biochemistry, 2001, Vol 129, Issue 6, p949
- ISSN
0021-924X
- Publication type
Article
- DOI
10.1093/oxfordjournals.jbchem.a002942