In vitro kinetics of the rat brain succinate dehydrogenase inhibition by hexachlorophene.

Abstract

Brain succinate dehydrogenase (SDH) activity was inhibited by in vitro hexachlorophene (HCP) with a half inhibitory concentration (IC50) of 0.65 x 10(-3) M. The HCP exerted noncompetitive inhibition at 0.5 mM (<IC50), uncompetitive inhibition at 0.65 mM (= IC50), and mixed-type inhibition at 0.8 mM (>IC50) on SDH activity. The brain SDH demands more energy of activation (deltaE) in the presence of HCP. The ionizable groups of SDH such as the sulfhydral group of cysteine and alpha-amino groups of cysteine were not altered qualitatively in the presence of HCP.