Molecular and Cellular Biochemistry

, Volume 103, Issue 1, pp 85–96

Role of sulfhydryl groups in phospholipid methylation reactions of cardiac sarcolemma

  • Roland Vetter
  • Jian Dai
  • Nasrin Mesaeli
  • Vincenzo Panagia
  • Naranjan S. Dhalla
Article

DOI: 10.1007/BF00229596

Cite this article as:
Vetter, R., Dai, J., Mesaeli, N. et al. Mol Cell Biochem (1991) 103: 85. doi:10.1007/BF00229596

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 heartsarcolemmaS-adenosyl-L-methioninephospholipid N-methylationneutral lipid methylationsulfhydryl groups

Abbreviations

AdoMet

S-Adenosyl-L-methionine

AdoHey

S-adenosyl-L-homocysteine

DTNB

5,5′dithiobis (2-nitrobenzoate)

NEM

N-ethylmaleimide

MMTS

methylmethanethiosulfonate

DTT

dithiothreitol

EDTA

Ethylenediaminetetraacetic acid

GSH

glutathione

GSSG

glutathione disulfide

PE

phosphatidylethanolamine

PMME

phosphatidyl-N-monomethylethamolamine

PDME

phosphatidyl-N-dimethylethanolamine

PC

phosphatidylcholine

NPL

nonpolar lipids

SL

sarcolemma

Copyright information

© Kluwer Academic Publishers 1991

Authors and Affiliations

  • Roland Vetter
    • 1
    • 2
  • Jian Dai
    • 1
    • 2
  • Nasrin Mesaeli
    • 1
    • 2
  • Vincenzo Panagia
    • 1
    • 2
  • Naranjan S. Dhalla
    • 1
    • 2
  1. 1.Division of Cardiovascular Sciences St. Boniface General Hospital Research CentreWinnipegCanada
  2. 2.Departments of Anatomy and Physiology, Faculty of MedicineUniversity of Manitoba WinnipegCanada