Skip to main content
NCBI home page
British Journal of Industrial Medicine logoLink to British Journal of Industrial Medicine
. 1985 May;42(5):305–311. doi: 10.1136/oem.42.5.305

Dechlorination of halocarbons by microsomes and vesicular reconstituted cytochrome P-450 systems under reductive conditions.

A G Salmon, J A Nash, C M Walklin, R B Freedman
PMCID: PMC1007477  PMID: 3986141

Abstract

A spectrophotometric assay of the reductive dechlorination of halocarbons was developed and used to determine the kinetic characteristics of dechlorination of a range of haloethanes catalysed by microsomes from rat and rabbit liver. Analysis of the typical reaction of hexachloroethane shows that the reaction is catalysed by cytochrome P-450 and results in the formation of olefinic products as well as less chlorinated alkanes: in other respects the reaction resembles that known to occur with carbon tetrachloride. The dechlorination of haloethanes catalysed by a vesicular reconstituted system of cytochrome P-450 enzymes from rabbit liver was also studied and found to be similar to that catalysed by microsomes: both reductase and a phenobarbital inducible form of cytochrome P-450 were essential. There is no substantial dependence of maximum dechlorination rate on compound structure, suggesting that the reduction of substrate is not the rate limiting step in the overall reaction. The main factor in determining the apparent binding constant to the enzyme is the partition coefficient into the lipid membrane, as assessed by calculated log P values.

Full text

PDF
305

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Burke M. D., Mayer R. T. Ethoxyresorufin: direct fluorimetric assay of a microsomal O-dealkylation which is preferentially inducible by 3-methylcholanthrene. Drug Metab Dispos. 1974 Nov-Dec;2(6):583–588. [PubMed] [Google Scholar]
  2. Eisenthal R., Cornish-Bowden A. The direct linear plot. A new graphical procedure for estimating enzyme kinetic parameters. Biochem J. 1974 Jun;139(3):715–720. doi: 10.1042/bj1390715. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. French J. S., Coon M. J. Properties of NADPH-cytochrome P-450 reductase purified from rabbit liver microsomes. Arch Biochem Biophys. 1979 Jul;195(2):565–577. doi: 10.1016/0003-9861(79)90383-7. [DOI] [PubMed] [Google Scholar]
  4. Fujii K., Miki N., Sugiyama T., Morio M., Yamano T., Miyake Y. Anaerobic dehalogenation of halothane by reconstituted liver microsomal cytochrome P-450 enzyme system. Biochem Biophys Res Commun. 1981 Sep 16;102(1):507–512. doi: 10.1016/0006-291x(81)91548-5. [DOI] [PubMed] [Google Scholar]
  5. Haugen D. A., van der Hoeven T. A., Coon M. J. Purified liver microsomal cytochrome P-450. Separation and characterization of multiple forms. J Biol Chem. 1975 May 10;250(9):3567–3570. [PubMed] [Google Scholar]
  6. Ingelman-Sundberg M., Glaumann H. Incorporation of purified components of the rabbit liver microsomal hydroxylase system into phospholipid vesicles. Biochim Biophys Acta. 1980 Jul;599(2):417–435. doi: 10.1016/0005-2736(80)90188-1. [DOI] [PubMed] [Google Scholar]
  7. LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
  8. Leo A., Jow P. Y., Silipo C., Hansch C. Calculation of hydrophobic constant (log P) from pi and f constants. J Med Chem. 1975 Sep;18(9):865–868. doi: 10.1021/jm00243a001. [DOI] [PubMed] [Google Scholar]
  9. Loew G., Trudell J., Motulsky H. Quantum chemical studies of the metabolism of a series of chlorinated ethane anesthetics. Mol Pharmacol. 1973 Mar;9(2):152–162. [PubMed] [Google Scholar]
  10. Nastainczyk W., Ahr H. J., Ullrich V. The reductive metabolism of halogenated alkanes by liver microsomal cytochrome P450. Biochem Pharmacol. 1982 Feb 1;31(3):391–396. doi: 10.1016/0006-2952(82)90187-3. [DOI] [PubMed] [Google Scholar]
  11. OMURA T., SATO R. THE CARBON MONOXIDE-BINDING PIGMENT OF LIVER MICROSOMES. II. SOLUBILIZATION, PURIFICATION, AND PROPERTIES. J Biol Chem. 1964 Jul;239:2379–2385. [PubMed] [Google Scholar]
  12. PHILLIPS A. H., LANGDON R. G. Hepatic triphosphopyridine nucleotide-cytochrome c reductase: isolation, characterization, and kinetic studies. J Biol Chem. 1962 Aug;237:2652–2660. [PubMed] [Google Scholar]
  13. Parry G., Palmer D. N., Williams D. J. Ligand partitioning into membranes: its significance in determining Km and Ks values for cytochrome P-450 and other membrane bound receptors and enzymes. FEBS Lett. 1976 Aug 15;67(2):123–129. doi: 10.1016/0014-5793(76)80348-1. [DOI] [PubMed] [Google Scholar]
  14. Salmon A. G. Cytochrome P-450 and the metabolism of vinyl chloride. Cancer Lett. 1976 Nov;2(2):109–113. doi: 10.1016/s0304-3835(76)80019-5. [DOI] [PubMed] [Google Scholar]
  15. Salmon A. G., Jones R. B., Mackrodt W. C. Microsomal dechlorination of chloroethanes: structure-reactivity relationships. Xenobiotica. 1981 Nov;11(11):723–734. doi: 10.3109/00498258109045876. [DOI] [PubMed] [Google Scholar]
  16. Sandermann H., Jr, Strominger J. L. Purification and properties of C 55 -isoprenoid alcohol phosphokinase from Staphylococcus aureus. J Biol Chem. 1972 Aug 25;247(16):5123–5131. [PubMed] [Google Scholar]
  17. Van Dyke R. A., Wineman C. G. Enzymatic dechlorination. Dechlorination of chloroethanes and propanes in vitro. Biochem Pharmacol. 1971 Feb;20(2):463–470. doi: 10.1016/0006-2952(71)90082-7. [DOI] [PubMed] [Google Scholar]
  18. Wolf C. R., King L. J., Parke D. V. Anaerobic dechlorination of trichlorofluoromethane by liver microsomal preparations in vitro. Biochem Soc Trans. 1975;3(1):175–177. doi: 10.1042/bst0030175. [DOI] [PubMed] [Google Scholar]
  19. Wolf C. R., Slaughter S. R., Marciniszyn J. P., Philpot R. M. Purification and structural comparison of pulmonary and hepatic cytochrome P-450 from rabbits. Biochim Biophys Acta. 1980 Aug 21;624(2):409–419. doi: 10.1016/0005-2795(80)90082-3. [DOI] [PubMed] [Google Scholar]
  20. van der Hoeven T. A., Coon M. J. Preparation and properties of partially purified cytochrome P-450 and reduced nicotinamide adenine dinucleotide phosphate-cytochrome P-450 reductase from rabbit liver microsomes. J Biol Chem. 1974 Oct 10;249(19):6302–6310. [PubMed] [Google Scholar]

Articles from British Journal of Industrial Medicine are provided here courtesy of BMJ Publishing Group

RESOURCES