THE FATTY-ACID COMPOSITION OF LIPIDS FROM THE WOOL CELL-MEMBRANE COMPLEX

The composition of the fatty acids from wool cell membrane lipids and chloroform/methanol extractable lipids from the intact fibre was studied by means of gas liquid chromatography (GLC) and GLC with mass spectrometry coupling (GC-MS) with special regard to the distribution of 18-methyl-eicosanoic acid in the free fatty acid and the polar lipid fraction. Free and cholesteryl ester bonded fatty acids were separated from those of the polar lipid fraction by preparative thin-layer chromatography. In the polar fraction, the following acids were identified by GC-MS: lauric (C12), myristic (C14), palmitic (C16), oleic (C18:1), stearic (C18), arachidic (C20), behenic (C22). lignoceric (C24) and cerotic acid (C26). In addition to the acids with straight chain and even chain number, 18-methyl-eicosanoic acid (C21a) was found to be one of the main ratty acid components in the polar lipid fraction (38%), but was only present in traces in the free fatty acid fraction of the cell membrane complex and only in minor amounts (2%) in the chloroform/methanol extractable lipids from the intact fibre. The lipid extract was further shown to contain proteinaceous material with about 64% of hydrophobic amino acid residues. This material is assumed to belong to the membrane portion of a trans-membrane protein in the cuticle and to be the source of 18-methyl-eicosanoic acid.