ISSN:
1573-4919
Keywords:
rat heart
;
sarcolemma
;
S-adenosyl-L-methionine
;
phospholipid N-methylation
;
neutral lipid methylation
;
sulfhydryl groups
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00229596
