Fatty acid synthesis in mitochondria of Euglena gracilis

Abstract

A malonyl‐CoA‐independent fatty acid synthetic system, different from the systems in other subcellular fractions, occurred in mitochondria of Euglena gracilis. The system had ability to synthesize fatty acids directly from acetyl‐CoA as both primer and C2 donor using NADH as an electron donor. Fatty acids were synthesized by reversal of β‐oxidation with the exception that enoyl‐CoA reductase functioned instead of acyl‐CoA dehydrogenase in degradation system. A fairly high activity of enoyl‐CoA reductase was found on various enoyl‐CoA substrates (C4–C12) with NADH or NADPH. Three species of enoyl‐CoA reductase, distinct from each other by their chain‐length specificity, were found in Euglena mitochondria, and one of them was highly specific for crotonyl‐CoA. It is also discussed that the mitochondrial fatty‐acid synthetic system contributes to wax ester fermentation, the anaerobic energy‐generating system found in the organism. Copyright © 1984, Wiley Blackwell. All rights reserved