The isolation of a new lipid, triphosphoinositide, and monophosphoinositide from ox brain

Abstract

A new phospholipid designated triphosphoinositide has been isolated from ox and guinea-pig brain. Analysis shows that this compound contains inositol, phosphate, glycerol and fatty acid in the molar ratios of 1 3 : 1 : 2. All of the fatty acid is acyl ester-linked. The lipid contains no nitrogen as an integral part of its molecule. Evidence is presented that triphosphoinositide is tightly attached to brain protein. Such a complex is probably a constituent of the phosphatido-peptide fraction described by Folch (1952). Pretreatment of the brain tissue with acetone partially breaks the linkage in the complex, and triphosphoinositide then becomes a component of the ''diphosphoinositide'' fraction of brain tissue. Monophosphoinositide has been isolated from brain tissue, and chemically characterized. Its degradation products on acid and alkaline hydrolysis indicate that it has the phosphatidyl structure (diacylglycerylphosphorylinositol).