Identification and characterization of chiroinositol-containing phospholipids from bovine liver

Glycosylphosphatidylinositols and phosphatidylinositols, postulated as precursor species of insulin mediators, were investigated for the presence of myoinositol, chiroinositol, glucosamine and galactosamine in their carbohydrate moities. Our study of bovine liver lipids shows heterogeneity in glycosylphosphatidylinositols with at least two species containing 96-97% chiroinositol and 95-100% galactosamine, with molar ratios of chiroinositol: phosphate: galactosamine: galactose: mannose (1:1.8:1:3:2 and 1:1.2:1:1.6:1). Another species contained predominantly myoinositol and glucosamine. Furthermore, we identified phosphatidylinositols with either myoinositol or chiroinositol present. Thus, distinct myoinositol and chiroinositol species of glycosylphosphatidylinositols and phosphatidylinositols are present in bovine liver.