Fasciculins properties

A large number of organic compounds reversibly or irreversibly inhibit AChE (Long, 1963), which bind either to the esteratic or the anionic subsite of AChE catalytic site or to the peripheral site of the enzyme. Most of them are synthetic substances, sometimes bearing insecticidal properties. Few natural inhibitors of AChE are known and, to date, fasciculins are the only known proteinic AChE... 

There is limited information about the toxicity, toxicokinetics, and toxicological properties of onchidal and additional data are needed to make a health effects-based risk assessment of the natural compound. Although fasciculins are much better known, data on toxicological properties and toxicokinetics will be of interest and usefiil for risk assessments despite it being generally accepted that the toxicity of this proteinic toxin occurs at very low doses. 

The hypholomins and fasciculins were isolated and purified in the form of their jpermethyl ethers and their structures deduced inter alia from the H-n.m.r. spectra of these derivatives. Some properties of these dipyrones and their ethers are summarised in Table 20. 

A large number of organic compounds reversible or irreversibly inhibits AChE (Long, 1963), which bind either to the esteratic or the anionic subsite of AChE catalytic site or to the peripheral site of the enzymes. Most of them are S5mthetic substances, sometimes with insecticidal properties. Few natural inhibitors of AChE are known and, to date, fasciculins are the only known proteinic AChE inhibitors. They have been shown to display a powerful inhibitory activity toward mammalian AChE. lodination of Fas3 provided a fully active and specific probe of fasciculin-binding sites on rat brain AChE (Marchot et al., 1993). These authors demonstrate that fasciculins bind on a peripheral site of AChE, distinct from the catalytic site and, at least partly, common with the sites on which some cationic inhibitors and the substrate in excess bind since phosphorylation of the catalytic serine (esteratic subsite) by [l,3- H]diisopro-pyl fluorophosphate can still occur on the Fas3. In the... 

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