Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

Heavy metals (Pb²⁺, Cu²⁺, Cd²⁺, and Zn²⁺) inhibited alcohol dehydrogenase (ADH) of rape (EC 1.1.1.1.); Pb²⁺ and Cd²⁺ ions affected the imidazole ring of histidine, Cu²⁺ and Zn²⁺ ions interacted with the sulphydryl groups of cysteine in the molecule of the enzyme. The coenzyme protected ADH from inactivation by Pb²⁺ and Cd²⁺, but did not protect it from Cu²⁺ and Zn²⁺. Ethanol in a ternary complex ADH-NAD⁺ -ethanol was a strong protecting agent from Pb²⁺ and Cd²⁺ ions. Nitrates inhibited rape ADH toward any substrate. Sulphates and fluorides had no effect. The S-triazine herbicides studied proved strong inhibitors of rape ADH (their K_i's corresponded to concentrations of the order 10^-4 mol 1^-1), occupying the binding site for the coenzyme. The herbicides interacted with the metallic component of the enzyme, to which the nicotinamide part of the coenzyme is bound.