(Acyl)polyamines

An acylpolyamines contains one (mainly) aromatic head moiety, a polyamine backbone chain of various length and an alkaline tail. Optionally, an amino acid linker, such as asparagine, can be part of the molecule. The combination of various head moieties with polyamine chains of different length and the optional hydroxylation or methylation of the amines lead to an almost infinite diversity of structures. As an example, the first fully characterized acylpolyamine, Arg 636, is shown above.

Acylpolyamines are neuroactive compounds with blocking activity on cationic-selective ion channels, namely Ca²⁺ channels, K⁺ channels and ionotropic receptors. In insects, polyamine toxins act as non-competitive inhibitors and cause reversible paralysis by the use-dependent blocking of activated postsynaptic glutamate receptor (GluR) channels. In the vertebrate nervous systems, acylpolyamines were found to inhibit the channels of GluRs, nicotinic acetylcholine receptors or capsaicin receptors.

Historically, acylpolyamines got trivial names. These names are a combination of two to four letters stating the species or family of the spider venom in which the toxin was found, and a number related to its nominal mass. This practice has several drawbacks. Isomeric structures demanded the extension of the trivial names with additional letters which was done randomly. In addition, acylpolyamines found in the venom of different spider species got several trivial names. The consequence is that the literature became confusing and cross references became very difficult. On venoMS we use the generic nomenclature for acylpolyamines introduced in 2001. The generic nomenclature uses abbreviations for the head groups, amino acid linkers and tail moieties. The polyamine chain is described by numbers representing the number of methylene groups in between the nitrogen atoms and a substitution of an amine is indicated in brackets. Therefore, the generic name of Arg 636 is 2,4-(OH)₂-PhAcAsn533Arg. Even though the generic names are slightly longer, they are distinct and provide structural information.