Fatty Acid Desaturation

The unsaturated fatty acids contained in human and animal tissues are mainly oleic acid (16:1△9), oleic acid (18:1△9), linoleic acid (18:2△9, 12), linolenic acid (18:3△9, 12, 15), arachidonic acid (20:4△5, 8, 11, 14), etc. Among them, the most common monounsaturated fatty acids, oleic acid and oleic acid, can be activated by the corresponding fatty acids and then dehydrogenated by acylCoAdesaturase. This type of enzyme exists in the smooth endoplasmic reticulum and is a mixed function oxidase; because the enzyme only catalyzes the formation of double bonds at △9, but cannot form double bonds between C10 and the terminal methyl group, linoleic acid (linoleate), linolenic acid (linolenate) and arachidonate (arachidonate) cannot be synthesized or synthesized insufficiently in the body. However, they are indispensable to the body, so they must be supplied by food, so they are called essential fatty acids.
Plant tissues contain desaturases that can form double bonds between C-10 and the terminal methyl group (i.e., ω3 and ω6), and can synthesize the above three polyunsaturated fatty acids. When linoleic acid is ingested, it can generate arachidonic acid after the carbon chain is lengthened and desaturated in the animal body.