Svatos, A; Kalinova, B; Boland, W

Insect Biochemistry and Molecular Biology [Insect Biochem. Mol. Biol.], vol. 29, no. 3, pp. 225-232, Mar 1999

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 palmitic acids {[2,2,3,4,5,5,6,6,7,8,9,9,11,12- super(2)H sub(14)]-(11R,12S)-1 and [2,2,3,4,5,5,6,6,7,8,9,9,11,12- super(2)H sub(14)]-(11S,12R)-1} as metabolic probes. The (11R,12S)-1 acid was converted in PGs of treated virgin females to labelled methyl (11Z)-hexadecenoate ([ super(2)H sub(14)]-2, Mw=282 Da). In incubations with the opposite enantiomer two deuterium atoms from (11S,12R)-1 were removed, yielding [ super(2)H sub(12)]-2 of Mw=280 Da. These results were confirmed by methylthiolation of [ super(2)H sub(14)]-2 and [ super(2)H sub(12)]-2 with a dimethyl disulfide/iodine mixture. Mass spectra of the DMDS adducts directly showed the distribution of deuterium atoms in the labelled methyl esters of 2. The data consistently indicate, 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-elimination of two hydrogen atoms.