Amperometric study of the inhibitory effect of carboxylic acids on tyrosinase |
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Authors: | Sarmiza Elena Stanca Ionel Catalin Popescu |
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Institution: | a Laboratory for Photonics and Interfaces, Institute of Molecular and Biological Chemistry, Swiss Federal Institute of Technology, Lausanne, Switzerland b Department of Physical Chemistry, University “Babes-Bolyai”, Cluj-Napoca 3400, Romania |
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Abstract: | A tyrosinase-modified Pt electrode, based on physical entrapment of the enzyme in agar–agar gel, was constructed and used to investigate the inhibitory effect of six carboxylic acids. At an applied potential of −50 mV versus saturated calomel electrode (SCE), the bioelectrode develops a fast, steady state response, linearly correlated with the phenol concentration up to 10 mg/l, with a sensitivity of 3.7 nA l/mg. A kinetic analysis of the amperometric response to phenol, recorded in the absence and in the presence of carboxylic acids (benzoic, 3-bromobenzoic, 4-ethylbenzoic, acetic, phenylacetic, 2-naphthylacetic acids), revealed that for the first four compounds the inhibition process corresponds to an uncompetitive one. Using the Lineweaver–Burk linearization the inhibition constants as well as the inhibition coefficients were calculated for the strong inhibitors: benzoic, 3-bromobenzoic, 4-ethylbenzoic and acetic acids. |
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Keywords: | Tyrosinase PPO inhibitors Agar–agar gel |
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