Effect of reduced glutathione on the metabolism of chloroaldehydes by rat liver aldehyde dehydrogenase

Abstract

The identification of chlorinated organic compounds in drinking supplies has resulted in an interest in the metabolism and toxicity of chlorinated aldehydes. Another possible factor in the metabolism of chloroaldehydes is the endogenaous tripeptide glutathione. The formation of glutathioneconjugates with chloroaldehydes may increase or decrease their rate of reaction with the aldehyde dehydrogenase enzyme. This study found that the rat liver aldehyde dehydrogenase isozymes lost activity with time regardless of storage conditions. In vitro assays of enzyme activity confirmed substrate specificity for the chloroaldehydes and the isozymes. The reaction rate of glutathione depletion by monochloroacetaldehyde was the highest of the aldehydes. The addition of glutathione to the activity assays resulted in a decrease in Vmax but few significant changes in the Km values. Glutathione concentration was depleted by aldehydes in solution. Glutathione effected the metabolism of aldehydes by aldehyde dehydrogenase isozymes.