| Abstract: | The pentane extract of the social spider, Anelosimus eximius (Araneae, Theridiidae), contains hydrocarbons, fatty acids and their methyl esters, and a series of novel propyl esters of long-chain methyl-branched fatty acids. The propyl esters comprise almost three-fourths of the extract and consist predominantly of odd-numbered carbon chain components. Mass spectrometric analyses of the propyl esters, their methyl esters and cyanide derivatives showed that mono-, di- and trimethyl branched components with methyl branches on even numbered carbons predominate. The major components are propyl 4,20- and 4,30-dimethylhentriacontanoate and propyl 6,20- and 6,30-trimethylhentriacontanoate. The hydrocarbon fraction consists of n-, monomethyl- and dimethylalkanes, containing a relatively high proportion of even-numbered carbon chain components. The abundance of even-numbered carbon chain length alkanes and odd-numbered carbon chain length fatty acyl groups, along with abundant methyl-branches suggest that the propionyl-CoA and its carboxylated product, methylmalonyl-CoA, play important roles in the biosynthesis of these unique waxes. Arch. Insect Biochem. Physiol. 36:295–314, 1997. © 1997 Wiley-Liss, Inc. |
