Open AccessRapid partial degradation of DDT by a cytochrome P ‐450 model system
Author(s) -
LANGEN Hanno,
EPPRECHT Thomas,
LINDEN Michael,
HEHLGANS Thomas,
GUTTE Bernd,
BUSER HansRudolf
Publication year - 1989
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1989.tb14885.x
Subject(s) - chemistry , cysteine , cytochrome , heme , hemin , amino acid , metabolism , degradation (telecommunications) , biochemistry , cytochrome p450 , stereochemistry , chromatography , enzyme , telecommunications , computer science
Heme compounds, in combination with a reducing agent and oxygen, can express various activities of cytochrome P ‐450 enzymes. In the present study it was found that a mixture of hemin and excess cysteine was able to degrade the insecticide DDT partially. The major products were three water‐soluble, non‐toxic conjugates of DDT metabolites with cysteine which had lost two or three of the five chlorine atoms of DDT per molecule and whose structures were elucidated by gas chromatography/mass spectrometry. In 0.05 M NH 4 HCO 3 , pH 7.7/ethanol (5:6, by vol.), the degradation reaction catalyzed by the hemin‐cysteine model system was at least 8 × 10 4 times faster than the uncatalyzed reaction. In the presence of a designed 24‐residues polypeptide or β‐casein, two DDT‐binding proteins, an additional fourfold increase in the rate of DDT degradation was observed. Although the concentrations of DDT and cysteine occurring in an organism would be expected to be lower than those in the expriments described, the formation of water‐soluble conjugates of DDT metabolites with cysteine (and other amino acids) could also play a role in metabolism and excretion of DDT in vivo .