acylchain

An acyl chain refers to the hydrocarbon tail of an acyl group, typically shown as R-CO-, where R is an alkyl or aryl group. The acyl group itself is formed from a carboxylic acid by removal of the hydroxyl group, and the resulting moiety can bond to another molecule through ester, amide, or thioester linkages. In biochemistry, the acyl chain is the nonpolar, hydrophobic portion found in many lipids and related molecules.

In lipids, fatty acyl chains are the long hydrocarbon tails that are esterified to glycerol or sphingosine to form triglycerides, phospholipids, sphingolipids, and related structures. Common chain lengths range from about 14 to 22 carbons. Chains can be saturated (no double bonds) or unsaturated (one or more cis double bonds). The degree of unsaturation and the chain length influence membrane fluidity, phase behavior, and melting temperature.

Biosynthesis and metabolism: Fatty acyl chains are produced mainly by fatty acid synthesis, which builds them from acetyl-CoA and malonyl-CoA in the cytosol, with subsequent elongation and desaturation occurring in cellular organelles such as the endoplasmic reticulum. They are activated to acyl-CoA thioesters for incorporation into lipids and for beta-oxidation, a catabolic process that trims the chain to yield acetyl-CoA and energy.

Function and significance: The properties of acyl chains determine the physical characteristics of membranes and energy storage capacity. They also participate in signaling and regulation, for example through protein acylation, where fatty acyl groups like palmitoyl or myristoyl are covalently attached to proteins, affecting localization and function.

Nomenclature: In lipid contexts, the term “fatty acyl chain” is common. Chain length and unsaturation are denoted as prefixes such as C16:0 (palmitoyl) or C18:1 (oleoyl).