Stability of Benzotriazole Derivatives with Free Cu, Zn, Co and Metal-Containing Enzymes: Binding and Interaction of Methylbenzotriazoles with Superoxide Dismutase and Vitamin B₁₂

Benzotriazole derivatives form very strong bonds with transition metals, and are the most widely used type of industrial corrosion inhibitor. Some benzotriazole derivatives have been implicated as hormone regulators which also carry the ability to induce uncoupling responses or otherwise inhibit respiration processes in some microorganisms. However, the mechanisms associated with benzotriazole toxicity and inhibition are unknown. Using Differential Pulse Polarography, the stability constants of commercially significant corrosion inhibitors, 4-and 5-methylbenzotriazole, coordinated with free Cu (II) and Co (III), were determined to be 10¹⁵ and 10⁸, respectively. Polarographic analyses were extended to confirm that methylbenzotriazole also binds the copper center(s) in the ubiquitous enzyme superoxide dismutase, and the Corrin site in the coenzyme cobalamin (vitamin B₁₂). These results suggest that the metal-chelating ability of this unique class of compounds may confer inhibition to certain enzyme systems. (paper)