Mono- and Di-phenolase Activities of Metal Substituted Urease.
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Accession number;04A0258621
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| Title;Mono- and Di-phenolase Activities of Metal Substituted Urease. |
| Author;
YAMAGUCHI KAZUYA
(Osaka Univ., Grad. Sch.)
NAGAO TAKAKO
(Osaka Univ., Grad. Sch.)
YANAGAWA MEGUMI
(Osaka Univ., Grad. Sch.)
SUZUKI SHIN'ICHIRO
(Osaka Univ., Grad. Sch.)
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Journal Title;Abstracts. Symposium on Biofunctional Chemistry
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Journal Code:L0836A
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ISSN:
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VOL.18th;NO.;PAGE.78-79(2003)
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| Figure&Table&Reference;FIG.3 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Tyrosinase catalyzes the ortho-hydroxylation of monophenols (monophenolase activity) and the oxidation of o-diphenols to o-quinones (diphenolase activity). The enzyme is believed to have coupled dinuclear copper active site similar to those of hemocyanin and catechol oxidase, where each of two copper ions is coordinated to three histidine imidazoles. Meanwhile urease, that catalyzes the hydrolysis of urea to form ammonia and carbamate, possesses a dinuclear Ni active site with the protein providing a bridging carbamylated lysine residue as well as an aspartyl and four histidyl ligands. The mono- and di-phenolase activities of Cu-urease were investigated. Although native urease or apo protein did not catalyze any oxidation reactions, Cu-urease was observed to have both of mono- and di-phenolase activities. Furthermore, K217A mutant of Cu-urease, which has no bridging amino acid residue of metal ions in the active site, was found to show higher tyrosinase activity than wild-type Cu-urease. (author abst.) |
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