Desaturaasit

Desaturaasit is a term used in some languages to denote desaturase enzymes, a class of membrane-bound proteins that catalyze desaturation of fatty acyl chains. In English-language biochemistry, the standard term is desaturase, or more specifically the names of individual enzymes such as stearoyl-CoA desaturase or fatty acid desaturases (FADS1, FADS2).

Desaturases introduce cis double bonds into saturated fatty acids, increasing their unsaturation. They act on various substrates and positions, with well-known examples including the delta-9 desaturation of stearoyl-CoA to oleoyl-CoA and delta-5 or delta-6 desaturations in polyunsaturated fatty acid biosynthesis. In plants and animals, desaturases operate mainly in the endoplasmic reticulum; in plants they can also function in plastids, contributing to the production of linoleic and alpha-linolenic acids.

Mechanistically, many desaturases are non-heme iron enzymes that use molecular oxygen and reducing equivalents, typically supplied by NADH or NADPH via cytochrome b5 and related reductases, to remove two hydrogen atoms and form a cis double bond. The reactions are regioselective, yielding specific double-bond positions critical for the resulting fatty acid profile.

Physiological relevance: desaturation modulates membrane fluidity and generates signaling lipids, including arachidonic and eicosapentaenoic acids. It influences lipid metabolism, inflammation, and development. Dysregulation can be linked to metabolic disorders and cardiovascular risks.

Nomenclature: while desaturaasit may appear in some contexts, standard references use desaturase for the enzyme class. See also fatty acid desaturation, FADS, SCD.