| Abstract: | It was shown that the efficiency of succinate-cytochrome c reductase inhibitors, i. e. neutral polar substances, negatively charged phenols and 2-hydroxy-3-alkyl-1.4-naphthoquinones, is increased with an increase in their hydrophobicity. Plotting-lg C50 versus lg P for all the three groups of inhibitors, the role of functional groups of the inhibitors in their binding to the corresponding sites of the respiratory chain was determined. The efficiency of inhibition by neutral polar substances does not depend on the chemical nature of the inhibitors and is described by the equation-lg C50 = 0.864 lg P + 0.222 (r = 0.99). The negatively charged group of dissociated phenols determines the specificity of the inhibitor binding to the terminal site of the succinate dehydrogenase complex and is involved in the inhibitor binding to the enzyme. The carbonyl group of 2-hydroxy-3-alkyl-1.4-naphthoquinones selectively increases the affinity and efficiency of binding of these inhibitors to the b-c1 site of the respiratory chain. |
