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Identification of two histidines as copper ligands in Streptomyces glaucescens tyrosinase.
Biochemisches Institut, Universität Zürich, Switzerland.
The physiochemical properties of wild type and two mutants of Streptomyces glaucescens tyrosinase are reported. The native enzyme contains two coppers at the active site which are EPR nondetectable. The two coppers react stoichiometrically with one hydrogen peroxide molecule giving rise to oxytyrosinase. Its optical features are similar to those reported earlier for a molluscan hemocyanin. The two mutants in which histidine-62 and -189 were changed to asparagine by site-directed mutagenesis have lost their enzymatic activity and their ability to bind oxygen and contain only one copper ion which is fully EPR detectable. The EPR parameters indicate that the remaining copper is in a tetragonally distorted ligand environment. These data are in agreement with His-62 and His-189 serving as copper ligands in S. glaucescens tyrosinase.
PMID: 2846043 [PubMed - indexed for MEDLINE]
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Cited by 5 PubMed Central articles
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Identification of copper ligands in Aspergillus oryzae tyrosinase by site-directed mutagenesis.
Nakamura M, Nakajima T, Ohba Y, Yamauchi S, Lee BR, Ichishima E.
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[Biochem J. 2000]
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Melanin production by Rhizobium meliloti GR4 is linked to nonsymbiotic plasmid pRmeGR4b: cloning, sequencing, and expression of the tyrosinase gene mepA.
Mercado-Blanco J, García F, Fernández-López M, Olivares J.
J Bacteriol. 1993 Sep; 175(17):5403-10.
[J Bacteriol. 1993]
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Albino mutants of Streptomyces glaucescens tyrosinase.
Jackman MP, Hajnal A, Lerch K.
Biochem J. 1991 Mar 15; 274 ( Pt 3):707-13.
[Biochem J. 1991]
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