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

Abstract

Conditions for the conversion of C 14 HCl 3 and C 14 Cl 4 to C 14 O 2 by liver homogenates were determined. The addition of a pyridine nucleotide in either the oxidized or reduced state was required for a significant C 14 O 2 production. This effect was abolished when the homogenate was denatured. Glutathione further increased the activity. The optimum pH for the oxidation of CHCl 3 to CO 2 lay between 8.0 and 8.5. The dehalogenation of CCl 4 was relatively insensitive to changes in the pH of the incubation medium. At least two enzymes are probably required for the formation of CO 2 from the chloromethanes, since both the microsomal and soluble fractions of the homogenate are required for activity. Production of CO 2 was inhibited by tetrahydrofolate and p-chloromercuribenzoate. Inhibition by the latter could be overcome by glutathione.The coenzyme requirements suggest that CHCl 3 may be reduced to CH 2 Cl 2 , then successively oxidized to formaldehyde and formic acid. However, the formation of significant quantities of these substances from CHCl 2 could not be demonstrated. Inhibition of formic acid oxidation did not affect the production of C 14 O 2 from C 14 HCl 3 . Radioactivity from C 14 HCl 3 was found in the protein of the homogenate.