Regulation of Ca(2+)-binding properties of calmodulin nitrite-anion and hydrogen peroxide

The effect of NO2- and H2O2 on Ca(2+)-binding properties of calmodulin has been studied. The decrease of Ca2+ affinity for calmodulin and limiting quantity of the sites of cation cross-linking by the protein molecule under the effect of 1 nM NO2 and 10 nM H2O2. The increase of the acting substances concentration above physiological one results in the considerable decrease of the observed effects. The investigation results indicate to possible inhibition of Ca(2+)-calmodulin-dependent cytosole reaction of the smooth-muscle cells under the effect of NO2 and H2O2, and this will result in the myometrium relaxation. At the same time the data from literature and results of the authors' experiments allow supposing the difference in the mechanisms of NO2 and H2O2 actions on these processes.