THE CONVERSION OF CARBON TETRACHLORIDE AND CHLOROFORM TO CARBON DIOXIDE BY RAT LIVER HOMOGENATES

Abstract

Conditions for the conversion of C14HCl3and C14Cl4to C14O2by liver homogenates were determined. The addition of a pyridine nucleotide in either the oxidized or reduced state was required for a significant C14O2production. This effect was abolished when the homogenate was denatured. Glutathione further increased the activity. The optimum pH for the oxidation of CHCl3to CO2lay between 8.0 and 8.5. The dehalogenation of CCl4was relatively insensitive to changes in the pH of the incubation medium. At least two enzymes are probably required for the formation of CO2from the chloromethanes, since both the microsomal and soluble fractions of the homogenate are required for activity. Production of CO2was inhibited by tetrahydrofolate and p-chloromercuribenzoate. Inhibition by the latter could be overcome by glutathione.The coenzyme requirements suggest that CHCl3may be reduced to CH2Cl2, then successively oxidized to formaldehyde and formic acid. However, the formation of significant quantities of these substances from CHCl2could not be demonstrated. Inhibition of formic acid oxidation did not affect the production of C14O2from C14HCl3. Radioactivity from C14HCl3was found in the protein of the homogenate.