The properties of theD6 desaturase/acetylenase from the mossCeratodon purpureusand theD12 acetylenase from the dicotCrepis alpinawere studied by expressing the encoding genes inArabidopsis thalianaandSaccharomyces cerevisiae. The acetylenase fromC. alpinaD12 desaturated both oleate and linoleate with about equal efficiency. The desaturation of oleate gave rise to 9(Z),12(E)- and 9(Z),12(Z)-octadeca-dienoates in a ratio of approximately 3 : 1. Experiments using stereospecifically deuterated oleates showed that the pro-Rhydrogen atoms were removed from C-12 and C-13 in the introduction of the 12(Z) double bond, .
