| The inhibition kinetics and thermodynamic changes of tyrosinase via the zinc ion. | |
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MedLine Citation:
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PMID: 17544347 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We found that Zn(2+) conspicuously inactivated tyrosinase in a mixed-type inhibition manner: the final level of residual activity was abolished at the equilibrium state with concentration of 0.25 mM Zn(2+). Changes of both K(m) and V(max) by various concentrations of Zn(2+) in Lineweaver-Burk plot were observed. To see whether Zn(2+) also induced conformational change of tyrosinase and how thermodynamical changes by ligand binding were occurred, the intrinsic fluorescence studies as well as calorimetric measurements were conducted. The results showed that the Zn(2+) binding to tyrosinase directly induced conformational change of tyrosinase, and the changes of thermodynamic parameters such as enthalpy (DeltaH), Gibbs free-energy (DeltaG), and entropy (DeltaS) were obtained as 60+/-7.0 kJ/mol, -14.54 kJ/mol and 248.53 J/(K mol), respectively. The inactivating effect of Zn(2+) on tyrosinase was completely prevented by incubation with bovine serum albumin, which has a Zn(2+) binding motif in its structure. We suggested that Zn(2+) ligand-binding affected the substrate's accessibility due to the conformational changes and thus, the complex type of inhibition has occurred with the calorimetric changes. |
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Authors:
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Hong-Yan Han; He-Chang Zou; Jun-Yeong Jeon; Ye-Jing Wang; Wei-An Xu; Jun-Mo Yang; Yong-Doo Park |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2007-05-05 |
Journal Detail:
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Title: Biochimica et biophysica acta Volume: 1774 ISSN: 0006-3002 ISO Abbreviation: Biochim. Biophys. Acta Publication Date: 2007 Jul |
Date Detail:
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Created Date: 2007-07-02 Completed Date: 2007-09-06 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0217513 Medline TA: Biochim Biophys Acta Country: Netherlands |
Other Details:
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Languages: eng Pagination: 822-7 Citation Subset: IM |
Affiliation:
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Department of Biology, College of Life Sciences, Soochow University, Suzhou 215123, PR China. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Cattle Copper / chemistry Dose-Response Relationship, Drug Ions Kinetics Melanins / chemistry Microscopy, Fluorescence Molecular Conformation Monophenol Monooxygenase / chemistry* Protein Binding Protein Conformation Thermodynamics Zinc / chemistry* gamma-Globulins / chemistry |
| Chemical | |
Reg. No./Substance:
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0/Ions; 0/Melanins; 0/gamma-Globulins; 7440-50-8/Copper; 7440-66-6/Zinc; EC 1.14.18.1/Monophenol Monooxygenase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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