Macromolecular complex formation between mycotoxin zearalenon and dophamine‐beta‐monooxygenase

Abstract

Micotoxin zearalenon (MZ) is produced by Fusarium and introduces the lactone of rezorcylic acid possessed the pronounced estrogenic effect on animal organism. Taking into consideration the influence of estrogens administration on catecholamine turnover rate of the brain we have investigated the influence of MZ on dopamine‐β‐monooxigenase (DBM) (EC 1. 14. 17. 1), which catalyzes the final reaction of noradrenalin formation from dopamine. Using lineweares‐Burk plots Km for tyramine and ascorbate and Vmax of DBM catalyzing reaction and high speed centrifugation we demonstrate the complex formation between MZ and DBM. The mechanisms of the proposed effect of MZ on DBM and the details of toxic action of MZ on biological systems of the organism are conditioned by abnormalities in different systems of metabolism especially phospholipids (PL), so far as it is known already that membrane‐bound DBM is phospholipid‐dependent enzymatic system. The activating effect of MZ on adrenaline formation is accompanied by the elevation of Ca ions concentration, which plays an important role in intensification of Ca2+‐dependent phospholipase A2 activity, and accelerates the deacylation of the neutral PL, especially phosphatidylcholines with the formation of high concentrations of lysophosphatidylcholines, unesterified fatty acids and products of their peroxidation. These compounds have a pronounced membranotoxic and membranolytic action, which are one of the main pathogenetic mechanisms at MZ poisoning. Using of combined treatment by sodium thiosulfate and Ca2+‐ds‐RNA leads to the normalization of MZ poisoning phenomena.