Article

Molecular and Cellular Biochemistry

, Volume 103, Issue 1, pp 85-96

Role of sulfhydryl groups in phospholipid methylation reactions of cardiac sarcolemma

  • Roland VetterAffiliated withDivision of Cardiovascular Sciences St. Boniface General Hospital Research CentreDepartments of Anatomy and Physiology, Faculty of Medicine, University of Manitoba Winnipeg
  • , Jian DaiAffiliated withDivision of Cardiovascular Sciences St. Boniface General Hospital Research CentreDepartments of Anatomy and Physiology, Faculty of Medicine, University of Manitoba Winnipeg
  • , Nasrin MesaeliAffiliated withDivision of Cardiovascular Sciences St. Boniface General Hospital Research CentreDepartments of Anatomy and Physiology, Faculty of Medicine, University of Manitoba Winnipeg
  • , Vincenzo PanagiaAffiliated withDivision of Cardiovascular Sciences St. Boniface General Hospital Research CentreDepartments of Anatomy and Physiology, Faculty of Medicine, University of Manitoba Winnipeg
  • , Naranjan S. DhallaAffiliated withDivision of Cardiovascular Sciences St. Boniface General Hospital Research CentreDepartments of Anatomy and Physiology, Faculty of Medicine, University of Manitoba Winnipeg

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

The effect of reagents that modify sulfur-containing amino acid residues in the phosphatidylethanolamine N-methyltransferase was studied in the isolated rat cardiac sarcolemma by employing S-adenosyl-L-[methyl-3H]methionine as a methyl donor. Dithiothreitol protected the sulfhydryl groups in the membrane and caused a concentration- and time-dependent increase of phospholipid N-methylation at three different catalytic sites. This stimulation was highest (9-fold) in the presence of 1 MM MgCl2 and 0.1 µM S-adenosyl-L-[methyl-3H]methionine at pH 8.0 (catalytic site 1), and was associated with an enhancement of Vmax without changes in Km for the methyl donor. Thiol glutathione was less stimulatory than dithiothreitol; glutathione disulfide inhibited the phosphatidylethanolamine N-methylation by 50%. The alkylating reagents, N-ethylmaleimide and methylmethanethiosulfonate, inhibited the N-methylation with IC5O of 6.9 and 14.1 µM, respectively; this inhibition was prevented by 1 mM dithiothreitol. These results indicate a critical role of sulfhydryl groups for the activity of the cardiac sarcolemmal phosphatidylethanolamine N-methyltransferase and suggest that this enzyme system in cardiac sarcolemma may be controlled by the glutathione/glutathione disulfide redox state in the cell.

Key words

rat heart sarcolemma S-adenosyl-L-methionine phospholipid N-methylation neutral lipid methylation sulfhydryl groups