Mammalian Δ-6 Fatty Acid Desaturase :

Abstract

Δ-6 Fatty acid desaturase was noted to catalyze the conversion of linoleic acid to γ-linolenic acid and α-linolenic acid to n-3 octadecatetraenoic acid through the insertion of a double bond at the Δ-6 position of the fatty acid substrate. In mammals and paticularly in humans, this is the first rate-limiting step in the biosynthesis of polyunsaturated fatty acids such as dihomo-γ-linolenic, arachidonic, and eicosapentaenoic acids, all known as precursors of eicosanoids. Δ-6 desaturating activity has been shown associated with physiological and clinical observation findings. Expression cloning of plant and mammalian Δ-6 desaturase genes has recently been achieved and has provided indication of a new group of cytochrome b5-fusion proteins. The key role of this enzyme in lipid metabolism is presently being studied at the molecular level.