stearoyl

Stearoyl refers to an acyl substituent derived from stearic acid (octadecanoic acid), consisting of an 18-carbon saturated chain attached to a carbonyl group (-CO-). In chemical nomenclature, the stearoyl group marks the acyl portion of esters, amides, thioesters, and other derivatives formed from stearic acid.

Stearoyl derivatives appear in various contexts. Stearoyl chloride is the acid chloride of stearic acid used to acylate alcohols and amines; stearoyl esters are esters of stearic acid (for example, triglycerides commonly feature stearoyl groups at glycerol positions). In biochemistry, stearoyl-CoA is the CoA thioester of stearic acid and serves as an activated substrate in lipid metabolism. Stearoyl groups can be attached to lipids and proteins in different biological processes, contributing to membrane structure and signaling.

Biological relevance centers on the metabolism of saturated long-chain fatty acids. Stearoyl-CoA is a substrate for desaturation by stearoyl-CoA desaturase to form oleoyl-CoA, which influences membrane fluidity, triglyceride synthesis, and energy homeostasis. The balance between stearoyl- and monounsaturated fatty acids in cellular lipids affects membrane properties and metabolic health.

Nomenclature notes: stearoyl denotes the acyl portion derived from stearic acid; the free fatty acid is stearic acid, a saturated 18-carbon fatty acid. The term is used across chemistry and biochemistry to describe derivatives and activated forms bearing the stearoyl group.