2001
DOI: 10.1093/oxfordjournals.jbchem.a002942
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A Novel Mixed Valence Form of Rhus vernicifera Laccase and Its Reaction with Dioxygen to Give a Peroxide Intermediate Bound to the Trinuclear Center

Abstract: Multicopper oxidase belongs to the class of enzyme containing four or more Cu centers in a protein molecule (1). The minimum functional unit of multicopper oxidase comprises a set of one type 1 Cu, one type 2 Cu, and a pair of type 3 Cus. The type 1 Cu functions as the electron mediator from a substrate to the trinuclear center composed of the type 2 Cu and type 3 Cus, where dioxygen is bound and reduced to two water molecules. All these copper sites are indispensable for the four-electron reduction of dioxyge… Show more

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Cited by 30 publications
(28 citation statements)
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“…These spectral features are very similar to those produced by a mercury-substituted or mixed valent laccase (13,14) and Cys-to-Ser mutants of bilirubin oxidase (15) and Fet3p (16), indicating that multicopper oxidases commonly pass through intermediate I. The intensity of intermediate I band was much higher at 340 nm (⑀ ϭ 9,000) than at 315-330 nm due to the resting trinuclear copper center (⑀ ϭ 4,500 -5,300) (Figs.…”
supporting
confidence: 55%
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“…These spectral features are very similar to those produced by a mercury-substituted or mixed valent laccase (13,14) and Cys-to-Ser mutants of bilirubin oxidase (15) and Fet3p (16), indicating that multicopper oxidases commonly pass through intermediate I. The intensity of intermediate I band was much higher at 340 nm (⑀ ϭ 9,000) than at 315-330 nm due to the resting trinuclear copper center (⑀ ϭ 4,500 -5,300) (Figs.…”
supporting
confidence: 55%
“…Two reaction intermediates have been detected during reactions of some multicopper oxidases. One of them, intermediate I, could be trapped by the following modified multicopper oxidases so as to interrupt the electron transfer from the type I copper: a plant laccase whose type I copper was substituted with mercury (13); a mixed valent laccase in which the type I copper was oxidized, but the trinuclear copper center was reduced (14); and a Cys 3 Ser mutant of bilirubin oxidase (15) and Fet3p (16) whose type I copper center became vacant. Although the trinuclear copper center must be fully reduced to produce intermediate I, it has been considered to be a twoelectron reduced form and, therefore, also called the peroxide intermediate (13,16).…”
mentioning
confidence: 99%
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“…The His456.458Lys mutant showed BO and ferroxidase activities, indicating that the electron from a substrate is finally transferred to dioxygen via type I Cu and the mutated trinuclear center (18)(19)(20)(21). However, the drastic decreases in the enzyme activities of His456.458Lys would have been brought about by the change in the redox potential of the type III Cu centers (the substitution of Lys for His would lower the redox potential of type III Cu, significantly suppressing the rate of intramolecular electron transfer) and/or by lowering of the affinity of the trinuclear center towards dioxygen (Table 2).…”
Section: His456458lys Mutant-mentioning
confidence: 99%
“…Intermediates I can be trapped during the course of reactions of the MCO derivatives such as: the Hg-substituted laccase at the T1Cu center, [7] the mixed valent laccase with T1Cu in the cupric state and T2Cu and T3Cus in the cuprous state, [8] CueO, [9] bilirubin oxidase, [10] and Fet3p, [11] in which the T1Cu site is vacant as a result of the replacement of the Cys ligand with Ser. Since the intermediate I does not have an electron paramagnetic resonance (EPR) signal ( Figure S1 in Supporting Information), [7][8][9][10][11] it has been proposed that a peroxide species is bound to the TNC in a -1,2-peroxofashion, and accordingly, one of the three copper ions remains in the cuprous state. However, direct evidence to support the presence of peroxide or the oxidation state of the copper centers in the TNC has not been published.…”
mentioning
confidence: 99%