Effect of Free Unsaturated Fatty Acids on Fatty Acid Desaturation by Liver Preparations*

Abstract

1. The influence of unsaturated fatty acids on the mono-unsaturation of stearic acid in vitro was investigated. 2. Poly-unsaturated fatty acids, such as linoleic and arachidonic acids remarkably depressed the desaturation of stearic acid-l-¹⁴C. Oleic acid was also inhibitory, but less so than poly-unsaturated acids. This inhibition is not due to lipid hydroperoxide formation. 3. The removal of free fatty acid from the soluble fraction of the enzyme preparation caused a significant elevation of desaturating activity. 4. Fatty acid desaturation is partially regulated by the amount of unsaturated fatty acid.