Article
Inhibition kinetics of green crab (Scylla serrata) alkaline phosphatase by zinc ions: a new type of complexing inhibition.
Department of Biological Science and Biotechnology, Center for Ocean Science and Engineering, Tsinghua University, Beijing, China.
Biochimica et Biophysica Acta (impact factor:
4.66).
03/2001;
1545(1-2):6-12.
DOI:10.1016/S0167-4838(00)00254-5
pp.6-12
Source: PubMed
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Citations (0)
- Cited In (3)
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Article: Inhibition kinetics of mushroom tyrosinase by copper-chelating ammonium tetrathiomolybdate.
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ABSTRACT: With a strategy of chelating coppers at tyrosinase active site to detect an effective inhibitor, several copper-specific chelators were applied in this study. Ammonium tetrathiomolybdate (ATTM) among them, known as a drug for treating Wilson's disease, turned out to be a significant tyrosinase inhibitor. Treatment with ATTM on mushroom tyrosinase completely inactivated enzyme activity in a dose-dependent manner. Progress-of-substrate reaction kinetics using the two-step kinetic pathway and dilution of the ATTM revealed that ATTM is a tight-binding inhibitor and high dose of ATTM irreversibly inactivated tyrosinase. Progress-of-substrate reaction kinetics and activity restoration with a dilution of the ATTM indicated that the copper-chelating ATTM may bind slowly but reversibly to the active site without competition with substrate, and the enzyme-ATTM complex subsequently undergoes reversible conformational change, leading to complete inactivation of the tyrosinase activity. Thus, inhibition by ATTM on tyrosinase could be categorized as complexing type of inhibition with a slow and reversible binding. Detailed analysis of inhibition kinetics provided IC50 at the steady-state and inhibitor binding constant (K(I)) for ATTM as 1.0+/-0.2 microM and 10.65 microM, respectively. Our results may provide useful information regarding effective inhibitor of tyrosinase as whitening agents in the cosmetic industry.Biochimica et Biophysica Acta 11/2005; 1726(1):115-20. · 4.66 Impact Factor -
Article: Inhibitory kinetics of beta-N-acetyl-D-glucosaminidase from prawn (Litopenaeus vannamei) by zinc ion.
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ABSTRACT: Prawn (Litopenaeus vannamei) beta-N-acetyl-D-glucosaminidase (NAGase, EC 3.2.1.52) is involved in the digestion and molting processes. Zinc is one of the most important metals often found in the pollutant. In this article, the effects of Zn(2+) on prawn NAGase activity for the hydrolysis of pNP-NAG have been investigated. The results showed that Zn(2+) could reversibly and noncompetitively inhibit the enzyme activity at appropriate concentrations and its IC(50) value was estimated to be 6.00 +/- 0.25 mM. The inhibition model was set up, and the inhibition kinetics of the enzyme by Zn(2+) has been studied using the kinetic method of the substrate reaction. The inhibition constant was determined to be 11.96 mM and the microscopic rate constants were also determined for inactivation and reactivation. The rate constant of the inactivation (k(+0)) is much larger than that of the reactivation (k(-0)). Therefore, when the Zn(2+) concentration is sufficiently large, the enzyme is completely inactivated. On increasing the concentration of Zn(2+), the fluorescence emission peak and the UV absorbance peak are not position shifted, but the intensity decreased, indicating that the conformation of Zn(2+)-bound inactive NAGase is stable and different from that of native NAGase. We presumed that Zn(2+) made changes in the activity and conformation of prawn NAGase by binding with the histidine or cysteine residues of the enzyme.International Union of Biochemistry and Molecular Biology Life 11/2008; 61(2):163-70. · 3.51 Impact Factor -
Article: Irreversible competitive inhibitory kinetics of cardol triene on mushroom tyrosinase.
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ABSTRACT: Cardol triene was first purified from cashew (Anacardium occidentale L.) nut shell liquid and identified by gas chromatography coupled to mass spectroscopy and nuclear magnetic resonance. The effects of this compound on the activity of mushroom tyrosinase were studied. The results of the kinetic study showed that cardol triene was a potent irreversible competitive inhibitor and the inactivation was of the complexing type. Two molecules of cardol triene could bind to one molecule of tyrosinase and lead to the complete loss of its catalytic activity. The microscopic rate constants were determined for the reaction of cardol triene with the enzyme. The anti-tyrosinase kinetic research of this study provides a comprehensive understanding of inhibitory mechanisms of resorcinolic lipids and is beneficial for the future design of novel tyrosinase inhibitors.Journal of Agricultural and Food Chemistry 12/2010; 58(24):12993-8. · 2.82 Impact Factor
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Keywords
apparent inactivation rate constant
association constant
complexing scheme
enzyme first reversibly
inactivation
inactivation reaction
kinetic course
single molecule reaction
slow reversible course
zinc ions
