Studies on the Conjugated Lipides

It was first suggested by Anderson (1) that an inositol-containing phospholipide was present in the tubercle bacillus.Later a phospholipide of this type was isolated by Klenk and Sakai (2), Woolley (3), and Folch and Woolley (4) from the ordinary phospholipide fractions of soy bean and brain respectively.Further studies have been carried on by many workers on this lipide and its components in plant and animal tissues.According to Carter and Celmer (5), inositol-containing lipides so far isolated from plant sources are mixtures containing carbohydrate and nitrogenous components which are difficult to separate.Moreover, Folch (6, 7) reported that inositol-containing lipides of soy bean and brain differ in that the former on hydrolysis yields inositol monophosphate and the latter inositol diphosphate.However, Folch was mainly concerned with the inositolphosphoric acid ester, leaving the elucidation of the chemical structure of this phospholipide to further investigation.In this laboratory Imai (8) has been engaged in the study of inositolcontaining lipide in soy bean for several years.We have extended his work and have tried to obtain the inositol phospholipide in purer form.We soon found that the nitrogen content of this phospholipide was almost negligible, suggesting that it does not contain a nitrogenous base.From this and from the findings of Folch (6, 7) we have assumed that the structure of inositol phospholipide might be of a phosphatidic acid type, inositol being combined with phosphoric acid.While we were carrying on experiments under this assumption, Faure and Morelec-Coulon (9) described the separation of a new phosphatidic acid from wheat germ which they named glyceroinositolphosphatidic acid, since the hydrolysis of this substance gave 2 moles of fatty acids (saturated and unsaturated), 1 mole of glycerol, 1 mole of phosphoric acid, and 1 mole of inositol.They proposed the accompanying formula as the probable structure of this lipide.More recently, Hawthorne and Chargaff (10) have taken up this problem and, following the separation methods of Folch and of Carter, have