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Your search keyword '"Puchkaev AV"' showing total 2 results
Start Over Author "Puchkaev AV" Topic iodides
2 results on '"Puchkaev AV"'

1. [Human thyroid peroxidase: inhibition of iodide ion and 3,3',5,5'-tetramethylbenzidine hydrolysis by phenol antioxidants].

Author

Grintsevich EA, Senchuk VV, Puchkaev AV, Shadyro OI, and Metelitsa DI

Subjects
Anions, Disulfides chemistry, Gallic Acid analogs & derivatives, Gallic Acid chemistry, Horseradish Peroxidase chemistry, Humans, Indicators and Reagents, Kinetics, Oxidation-Reduction, Phenylalanine analogs & derivatives, Antioxidants chemistry, Benzidines chemistry, Iodide Peroxidase chemistry, Iodides chemistry, Phenols, Phenylalanine chemistry
Abstract

A comparative kinetic study on the poly(gallic acid disulfide) (poly(DSGA)) inhibition of the iodide ion oxidation and on the 2-hydroxy-3,5-di-tert-butyl-N-phenylaniline (butaminophene) inhibition of 3,3',5,5'-tetramethylbenzidine (TMB) oxidation involving human thyroid peroxidase (hTPO) and horseradish peroxidase (HRP) was performed. The inhibition processes were characterized with the inhibition constants Ki and stoichiometric inhibition coefficients f, indicating the number of radical particles perishing on one inhibitor molecule. In the case of poly(DSGA), the Ki values for the I- oxidation were 0.60 and 0.04 microM, and the coefficients f were 13.6 and 16.5 for hTPO and HRP, respectively, which evidences the regeneration and high effectiveness of the polymeric inhibitor. In the case of butaminophene, the Ki values for TMB oxidation were 38 and 46 microM for hTPO and HRP, respectively. The coefficients f were 1.33 and 1.47, respectively, to reveal that butaminophene does not regenerate. The inhibition mechanisms for I- and TMB oxidation involving the two peroxidases are discussed.

Published
2000

2. Propyl gallate inhibition of iodide and tetramethylbenzidine oxidation catalyzed by human thyroid peroxidase.

Author

Grintsevich EE, Senchuk VV, Puchkaev AV, and Metelitza DI

Subjects
Antioxidants pharmacology, Benzidines chemistry, Enzyme Inhibitors pharmacology, Horseradish Peroxidase antagonists & inhibitors, Horseradish Peroxidase metabolism, Humans, Iodide Peroxidase antagonists & inhibitors, Iodides chemistry, Oxidation-Reduction drug effects, Propyl Gallate chemistry, Benzidines metabolism, Iodide Peroxidase metabolism, Iodides metabolism, Propyl Gallate pharmacology
Abstract

The kinetic characteristics (kcat, Km, and their ratio) for oxidation of iodide (I-) at 25 degrees C in 0.2 M acetate buffer, pH 5.2, and tetramethylbenzidine (TMB) at 20 degrees C in 0.05 M phosphate buffer, pH 6.0, with 10% DMF catalyzed by human thyroid peroxidase (HTP) and horseradish peroxidase (HRP) were determined. The catalytic activity of HRP in I- oxidation was about 20-fold higher than that of HTP. The kcat/Km ratio reflecting HTP efficiency was 35-fold higher in TMB oxidation than that in I- oxidation. Propyl gallate (PG) effectively inhibited all four peroxidase processes and its effects were characterized in terms of inhibition constants Ki and the inhibitor stoichiometric coefficient f. For both peroxidases, inhibition of I- oxidation by PG was characterized by mixed-type inhibition; Ki for HTP was 0.93 microM at 25 degrees C. However, in the case of TMB oxidation the mixed-type inhibition by PG was observed only with HTP (Ki = 3.9 microM at 20 degrees C), whereas for HRP it acted as a competitive inhibitor (Ki = 42 microM at 20 degrees C). A general scheme of inhibition of iodide peroxidation containing both enzymatic and non-enzymatic stages is proposed and discussed.

Published
2000

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