The phenylthiourea is a competitive inhibitor of the enzymatic oxidation of DOPA by phenoloxidase.

06:00 EDT 4th May 2011 | BioPortfolio

Summary of "The phenylthiourea is a competitive inhibitor of the enzymatic oxidation of DOPA by phenoloxidase."

Phenoloxidase is a key enzyme of melanization catalyzing the oxidation of phenols. Phenylthiourea (PTU) is the well-known and widely used inhibitor of phenoloxidase. However, the mechanism of its action is not quite clear. In the present work, the effect of PTU on the enzymatic oxidation of 3-(3,4-dihydroxyphenyl)-l-alanine (DOPA) by phenoloxidase was studied by spectrophotometric methods. The inhibition constant of PTU was estimated as 0.21 ± 0.09 µM and the competitive type of inhibition was determined for this reaction.


Institute of Chemical Kinetics and Combustion, Laboratory of Chemistry and Physics of Free Radicals, Institutskaya 3, Novosibirsk, Russian Federation.

Journal Details

This article was published in the following journal.

Name: Journal of enzyme inhibition and medicinal chemistry
ISSN: 1475-6374


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Medical and Biotech [MESH] Definitions

One of the AROMATIC-L-AMINO-ACID DECARBOXYLASES, this enzyme is responsible for the conversion of dopa to dopamine. It is of clinical importance in the treatment of Parkinson's disease. EC

Isoprostanes derived from the free radical oxidation of ARACHIDONIC ACID. Although similar in structure to enzymatically synthesized prostaglandin F2alpha (DINOPROST), they occur through non-enzymatic oxidation of cell membrane lipids.

An enzyme of the oxidoreductase class that catalyzes the reaction between L-tyrosine, L-dopa, and oxygen to yield L-dopa, dopaquinone, and water. It is a copper protein that acts also on catechols, catalyzing some of the same reactions as CATECHOL OXIDASE. EC

A cytochrome oxidase inhibitor which is a nitridizing agent and an inhibitor of terminal oxidation. (From Merck Index, 12th ed)

An inhibitor of DOPA DECARBOXYLASE, preventing conversion of LEVODOPA to dopamine. It is used in PARKINSON DISEASE to reduce peripheral adverse effects of LEVODOPA. It has no antiparkinson actions by itself.


Relevant Topic

Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical re...