Fatty Chains of Acyl, Alkenyl, and Alkyl Phosphoglycerides of Rabbit Sarcoplasmic Reticulum

Choline and ethanolamine phosphoglyceride fractions were isolated from the lipid extract of rabbit sarcoplasmic reticulum. The fatty chains of the diacyl, 1-O-alkenyl-2-acyl and l-O-alkyl-2-acyl components were analyzed by selective acidic, alkaline, and enzymatic hydrolyses. Similar compositions of fatty chains at the 1- and 2-positions of l-O-alkenyl-2-acyl and l-O-alkyl-2-acyl components were observed, whereas significant differences were found between the diacyl and the other two components in ethanolamine phospho-glycerides. For choline phosphoglycerides, no structural relationship between the diacyl and the other two components could be definitely determined. These findings suggest that a metabolic relationship between the 1-O-alkenyl and 1-O-alkyl moieties may exist and, in the ethanolamine fraction, an intimate relationship of the diacyl component with ether-type phosphoglycerides can be excluded.