delta5desaturase

Delta-5 desaturase, also known as delta-5 desaturase or D5 desaturase, is an enzyme involved in fatty acid metabolism that introduces a cis double bond at the fifth carbon from the carboxyl end (the delta-5 position) of certain polyunsaturated fatty acids. It catalyzes the desaturation step that converts dihomo-gamma-linolenic acid (20:3n-6) to arachidonic acid (20:4n-6) in the omega-6 pathway, and converts eicosatetraenoic acid (20:4n-3) to eicosapentaenoic acid (20:5n-3) in the omega-3 pathway.

In humans, the enzyme is encoded by the FADS1 gene and operates as part of the microsomal fatty acid desaturase system, typically relying on the NADH-cytochrome b5 reductase pathway and cytochrome b5 for electron transfer. It is widely expressed, with notable activity in the liver and other tissues capable of synthesizing long-chain polyunsaturated fatty acids.

Regulation of delta-5 desaturase is influenced by dietary fatty acids and hormonal signals, and genetic variation in FADS1 can affect enzyme activity and the resulting fatty acid profile of tissues. Environmental and physiological factors that alter desaturase activity can impact the balance of long-chain polyunsaturated fatty acids available for lipid signaling and membrane structure.

Delta-5 desaturase is of interest in metabolic engineering and nutrition because it governs key steps in the production of arachidonic acid and EPA. In such applications, the enzyme is used to enhance LC-PUFA synthesis in plants and microorganisms, supporting the production of important dietary lipids.