Isolation and chemical characterization of phosphatidyl glycerol from spinach leaves

Abstract

Pure phosphatidyl glycerol was obtained from spinach leaves after repeated chromatography on silica columns. Ascertainment of the configuration of the hydrolysis products formed by the action of phospholipases C (EC 3.1.4.3) and D (EC 3.1.4.4) demonstrated that this phospholipid is identical with 1,2-diacyl-glycerol-3-phosphoryl-1-glycerol. Fatty acid analysis of several lipid fractions showed that the Δ3-trans-hexadecenoic acid, present in the leaves, is concentrated almost exclusively in phosphatidyl glycerol. Degradation experiments with phospholipase A (EC 3.1.1.4) showed that this acid is located preferentially at the 2-ester position. A subfractionation of phosphatidyl glycerol was accomplished by thin-layer chromatography on silica plates impregnated with silver nitrate. A breakdown of the two fractions obtained with phospholipase A allowed the recognition of several molecular species, and 1-linolenoyl,2-Δ3-trans-hexadecenoyl-glycerol-3-phosphoryl-1′-glycerol appeared to be the major species. The results were confirmed by hydrolysis of phosphatidyl glycerol with phospholipase C and separation on impregnated adsorbents of the diglycerides formed.