Stereochemistry of lepidopteran sex pheromone biosynthesis: a comparison of fatty acid CoA Delta 11-(Z)-desaturases in Bombyx mori and Manduca sexta female moths

The absolute stereochemistry of fatty acid (FA) desaturation in Bombyx mori and Manduca sexta female pheromone glands (PGs), catalysed by FA-CoA Delta 11-(Z)-desaturases, was determined using chiral, specifically labelled pal mitic acids {[2,2,3,4,5,5,6,6,7,8,9,9,11,12-H-2(14)]-(11R,12S)-1 and [2,2,3 ,4,5,5,6,6,7,8,9,9,11,12-H-2(14)]-(11S,12R)-1} as metabolic probes. The (11 R,12S)-1 acid was converted in PGs of treated virgin females to labelled me thyl (11Z)-hexadecenoate ([H-2(14)]-2, Mw=282 Da). In incubations with the opposite enantiomer two deuterium atoms from (11S,12R)-1 were removed, yiel ding [H-2(12)]-2 of Mw=280 Da. These results were confirmed by methylthiola tion of [H-2(14)]-2 and [H-2(12)]-2 With a dimethyl disulfide/iodine mixtur e. Mass spectra of the DMDS adducts directly showed the distribution of deu terium atoms in the labelled methyl esters of 2. The data consistently indi cate, that the studied insects possess Delta 11-(Z)-desaturases with pro-(R ) C(11)-H and pro-(R) C(12)-H stereospecificity, catalysing a syn-eliminati on of two hydrogen atoms. (C) 1999 Elsevier Science Ltd. All rights reserve d.