Mitochondrial Fatty Acid Biosynthesis

Abstract

Mitochondria derived from liver have been used to study fatty acid synthesis in several species. Of the species studied, namely beef, bird (domestic hen), fish, lizard, mouse and rat, all have been shown to possess a mitochondrial fatty acid chain elongation system, distinct and separate from the reverse of B-oxidation. The system requires acetate as carbon donor, NADH as cofactor, and displays a broad primer specificity, fatty acids in the range n-C4 to n-C20 all being elongated, by the addition of three or four acetate units, with equal facility. Only the system derived from hen was primer specific, acids in the range n-C12 not being elongated. The elongated fatty acids were preferentially incorporated into the phospholipid fraction of the mitochondrion. The properties of each liver mitochondrial elongation system were similar to the elongation system derived from heart sarcosomes for the same species. The presence of a liver mitochondrial de novo fatty acid synthesising system has been demonstrated for several, but not all, species. This system requires acetate as substrate, forming saturated C16 and C18 acids.