PTERIDINE-DEPENDENT OXYGEN ACTIVATION IN NEUTROPHILS
M. G. Petukh,1,* G. N. Semenkova,1 D. Fuchs,2 S. N. Cherenkevich 1
1 Department of Biophysics, Bclarusian State University, Minsk, and
2 Medical University, Bioccnter, Innsbruck, Austria;
* e-mail: margo_petuch@yahoo.com
We investigated the influence of neopterin and 7, 8-dihydroneopterin on the activity and secretory degranu-lation of myeloperoxidase in neutrophils and the ability of
pteridines to interact with the main substrate of this enzyme, hydrogen peroxide, and with the intermediate product of halogenation cycle - hypochlorous acid. It was shown
that neopterin and 7, 8-dihydroneopterin while being a redox-pair regulated the process of oxygen activation in neutrophils by functioning of myeloperoxidase. Depending on
concentration, pteridines can influence the secretion of myeloperoxidase into intracellular medium and decrease the level of hydrogen peroxide and hypochlorous acid that are
a substrate and an intermediate product of the enzyme respectively. It was shown that 7, 8-dihydroneopterin in micromolar concentration appeared to be noncompetitive
inhibitor of myeloperoxidase. We suppose that myeloperoxidase assists 7, 8-dihydroneopterin oxidation by hypochlorous acid that leads to neopterin concentration increase.
These changes modify the concentration of reactive oxygen species in intracellular and extracellular media.
Key words: neopterin, 7, 8-dihydroneopterin, myeloperoxidase, reactive oxygen species
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