Fatty Acid Desaturase

A fatty acid desaturase is an enzyme that removes two hydrogen atoms from a fatty acid, creating a carbon/carbon double bond. These desaturases are classified as

• delta - indicating that the double bond is created at a fixed position from the carboxyl group of a fatty acid (for example, Δ9desaturase creates a double bond at the 9th position from the carboxyl end).
• omega (e.g. ω3desaturase) - indicating the double bond is created between the third and fourth carbon from the methyl end of the fatty acid.

In the biosynthesis of essential fatty acids, an elongase alternates with different desaturases (for example, Δ6desaturase) repeatedly inserting an ethyl group, then forming a double bond.