Biomaterial Database

Horseradish peroxidase inhibition by thiouracils. 1995

A M Zatón, and E Ochoa de Aspuru

Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, Facultad de Farmacia, Vitoria-Gasteiz, España.

In this paper, the activity of horseradish peroxidase was further determined in the presence of several uracil derivatives. The rate of guaiacol peroxidation decreases in presence of 2-thiouracil and of 6-n-propyl-2-thiouracil, but is not changed by 6-n-propyluracil nor uracil. Thus, thiouracils inhibit horseradish peroxidase in a noncompetitive form. The binding of 6-n-propyl-2-thiouracil, 2-thiouracil, 6-n-propyluracil and uracil with horseradish peroxidase shows difference spectra due to changes in the environment of heme group in peroxidase. Then, the binding sites for these uracil derivatives are in an hydrophobic pocket at the heme periphery of peroxidase. The lesser binding rates were for uracil and propyluracil, which did not inhibit the peroxidase activity. These results point to the thiol group in uracils as responsible for the inhibition of peroxidase activity through interaction with an allosteric binding site, in peroxidase heme environment.

UI	MeSH Term	Description	Entries
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D006735	Horseradish Peroxidase	An enzyme isolated from horseradish which is able to act as an antigen. It is frequently used as a histochemical tracer for light and electron microscopy. Its antigenicity has permitted its use as a combined antigen and marker in experimental immunology.	Alpha-Peroxidase,Ferrihorseradish Peroxidase,Horseradish Peroxidase II,Horseradish Peroxidase III,Alpha Peroxidase,II, Horseradish Peroxidase,III, Horseradish Peroxidase,Peroxidase II, Horseradish,Peroxidase III, Horseradish,Peroxidase, Ferrihorseradish,Peroxidase, Horseradish
D013056	Spectrophotometry, Ultraviolet	Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Ultraviolet Spectrophotometry
D013889	Thiouracil	Occurs in seeds of Brassica and Crucifera species. Thiouracil has been used as antithyroid, coronary vasodilator, and in congestive heart failure although its use has been largely supplanted by other drugs. It is known to cause blood dyscrasias and suspected of terato- and carcinogenesis.
D013956	Antithyroid Agents	Agents that are used to treat hyperthyroidism by reducing the excessive production of thyroid hormones.	Antithyroid Agent,Antithyroid Drug,Goitrogen,Goitrogens,Thyroid Antagonists,Antithyroid Drugs,Antithyroid Effect,Antithyroid Effects,Agent, Antithyroid,Agents, Antithyroid,Antagonists, Thyroid,Drug, Antithyroid,Drugs, Antithyroid,Effect, Antithyroid,Effects, Antithyroid
D014498	Uracil	One of four nucleotide bases in the nucleic acid RNA.