Partial release of covalently bound 18-methyleicosanoic acid from wool cuticle with primary alcohols

The stability of the bond of 18-methyleicosanoic acid (18-MEA) from untreat ed and chlorinated wool towards transesterification by alcohols was investi gated. The extraction of untreated wool top with methanol not only dissolve s the readily solvent-extractable lipids, but also the methyl esters of pal mitic acid and 18-MEA from the cuticle proteolipids. About 10% of the total amount of 18-MEA is released by a 100 h Soxhlet-extraction with methanol f rom untreated top. With methanol replaced by ethanol, the ethyl esters of 1 8-MEA were detected. Transesterification of the 18-MEA proteolipids with th e secondary alcohol 2-propanol was not observed. The treatment of wool with formic acid resulted in the removal of the soluble tell membrane lipids fr om the fibre but not in the release of 18-MEA. However, the removal of cell membrane compounds by solvents was shown to increase the accessibility of the 18-MEA-proteolipid regions for transesterification, and the influence o f industrial chlorination is even more pronounced. These findings support t he view that a significant part of the 18-MEA is bound to membrane domains of cuticular membrane proteins. The major portion of 18-MEA-containing prot eolipids, however, is localized in areas of the fibre which are not accessi ble after modification of the cell membrane complex with solvents or by ind ustrial chlorination.