Submitted on October 28, 2002
Revised on December 11, 2002
Accepted on December 12, 2002
Separate myocardial ethanolamine phosphotransferase activities responsible for plasmenylethanolamine and phosphatidylethanolamine synthesis
David A. Ford
Biochemistry, Saint Louis University, School of Medicine, St. Louis, MO 63104
Corresponding Author: fordda{at}slu.edu
Ethanolamine phosphotransferase is a key enzyme responsible for the synthesis of ethanolamine glycerophospholipids. Plasmenylethanolamine is a predominant molecular subclass of ethanolamine glycerophospholipids in the heart. The present study was designed to identify the selective use 1-O-alk-1'-enyl-2-acyl-sn-glycerol as a substrate for ethanolamine phosphotransferase as a mechanism responsible for the predominance of plasmenylethanolamine in the rabbit heart. Ethanolamine phosphotransferase activity in rabbit myocardial membranes using 1,2-diacyl-sn-glycerol as substrate is activated by Mn++, inhibited by DTNB and is unaffected by Ca++. In contrast, ethanolamine phosphotransferase activity using 1-O-alk-1'-enyl-2-acyl-sn-glycerol as substrate is inhibited by Mn++ and Ca++, but is activated by DTNB. Additionally, ethanolamine phosphotransferase activity using 1-O-alk-1'-enyl-2-acyl-sn-glycerol substrate was more sensitive to thermal denaturation compared to that with 1,2-diacyl-sn-glycerol. Taken together, these results suggest that separate ethanolamine phosphotransferase activities are present in heart membranes that are responsible for the synthesis of phosphatidylethanolamine and plasmenylethanolamine.
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