Alpha-amanitin

α-Amanitin

Names
Other names (cyclic L-asparaginyl-4-hydroxy-L-proly-(R)-4,5-dihydroxy-L-isoleucyl-6-hydroxy-2-mercapto-L-tryptophylglycyl-L-isoleucylglycyl-L-cysteinyl) cyclic (4 → 8)-sulfide(R)-S-oxide.
Identifiers
CAS Number	23109-05-9 N
3D model (Jmol)	Interactive image
ChEBI	CHEBI:37415 N
ChemSpider	16735655 Y
ECHA InfoCard	100.041.287
PubChem	2100
InChI InChI=1S/C39H54N10O14S/c1-4-16(2)31-36(60)42-11-29(55)43-25-15-64(63)38-21(20-6-5-18(51)7-22(20)46-38)9-23(33(57)41-12-30(56)47-31)44-37(61)32(17(3)27(53)14-50)48-35(59)26-8-19(52)13-49(26)39(62)24(10-28(40)54)45-34(25)58/h5-7,16-17,19,23-27,31-32,46,50-53H,4,8-15H2,1-3H3,(H2,40,54)(H,41,57)(H,42,60)(H,43,55)(H,44,61)(H,45,58)(H,47,56)(H,48,59)/t16?,17?,19?,23-,24-,25-,26-,27-,31-,32-,64+/m0/s1 Y Key: CIORWBWIBBPXCG-NUCBJAHASA-N Y
SMILES O=C(NCC(N[C@@](C(NCC(N[C@@H](C3)C(N[C@@H](CC(N)=O)C(N5[C@H]4C[C@@H](O)C5)=O)=O)=O)=O)([H])[C@@H](C)CC)=O)[C@H](CC1=C(S3=O)NC2=C1C=CC(O)=C2)NC([C@@]([C@@H](C)[C@@H](O)CO)([H])N[C@@]4=O)=O
Properties
Chemical formula	C39H54N10O14S
Molar mass	918.97 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

alpha-Amanitin or α-amanitin is a cyclic peptide of eight amino acids. It is possibly the most deadly of all the amatoxins, toxins found in several species of the Amanita genus of mushrooms, one being the death cap (Amanita phalloides) as well as the destroying angel, a complex of similar species, principally A. virosa and A. bisporigera. It is also found in the mushrooms Galerina marginata and Conocybe filaris. The oral LD₅₀ of amanitin is approximately 0.1 mg/kg for rats.

The structure of the polypeptide is atypical of most polypeptides, due to the branching of the amino acid chain. A cross bridge between 6-hydroxy-tryptophan and cysteine allows the formation of a second "inner loop". The "outer loop" is formed by the normal peptide bond of the carboxyl terminus to the amino terminus of the peptide chain.

Unlike most cyclic peptides, amatoxins (and phallotoxins) are synthesized on ribosomes. The genes encoding the proprotein for α-amanitin belongs to the same family as those that encode for phallacidin (a phallotoxin).

α-Amanitin is an selective inhibitor of RNA polymerase II and III. This mechanism makes it a deadly toxin.

α-Amanitin can also be used to determine which types of RNA polymerase are present. This is done by testing the sensitivity of the polymerase in the presence of α-amanitin. RNA polymerase I is insensitive, RNA polymerase II is highly sensitive (inhibited at 1μg/ml), RNA polymerase III is moderately sensitive (inhibited at 10μg/ml), and RNA polymerase IV is slightly sensitive (inhibited at 50μg/ml).