Amavadin
Amavadin is a vanadium-containing anion found in three species of poisonous Amanita mushrooms: A. muscaria, A. regalis, and A. velatipes.[1] Amavadin was first isolated and identified in 1972 by Kneifel and Bayer.[2] This anion, which appears as a blue solution, is an eight-coordinate vanadium complex.[1] A Ca2+ cation is often used to crystallize amavadin to obtain a good quality X-ray diffraction.[1] Oxidized amavadin can be isolated as its PPh4+ salt. The oxidized form contains vanadium (V), which can be used to obtain an NMR spectrum.[3]
Preparation
The formation of amavadin begins with the formation of two tetradentate ligands.[3]
- 2 HON(CH(CH3)CO2H)2 + VO2+ → [V{NO[CH(CH3)CO2]2}2]2- + H2O + 4H+
Structure and properties
The ligand found in amavadin was first synthesized in 1954.[4] Amavadin contains vanadium (IV). Initially, amavadin was thought to have a vanadyl, VO2+, center. In 1993, it was discovered by crystallographic characterization that amavadin is not a vanadyl ion compound. Instead, it is an octacoordinated vanadium (IV) complex. This complex is bonded to two tetradentate ligands derived from N-hydroxyimino-2,2'-dipropionic acid, H3(HIDPA), ligands.[5] The ligands coordinate through the nitrogen and the three oxygen centers. thumb| left| Amanita muscaria contains amavadin
Amavadin is a C2-symmetric anion with a 2- charge. The two-fold axis bisects the vanadium atom perpendicular to the two NO ligands. The anion features five chiral centers, one at vanadium and the four carbon atoms having S stereochemistry.[1] There are two possible diastereomers for the ligands, (S,S)-(S,S)-Δ and (S,S)-(S,S)-Λ.
The biological function of amavadin is still unknown, yet it has been thought that it uses H2O2 and acts as a peroxidase to aid the regeneration of damaged tissues.[3] Amavadin may serve as a toxin for protection of the mushroom.[6]
References
- ↑ a b c d Berry, R.E.; Armstrong, E.M.; Beddoes, R.L.; Collison, D.; Ertok, S.N.; Helliwell, M.; Garner, C.D. “The Structural Characterization of Amavadin.” Angew. Chem. Int. Ed. 1999, 38:6, pp. 795-797. Vorlage:Cite doi.
- ↑ Kneifel, H.; Bayer, E. “Stereochemistry and total synthesis of amavadin, the naturally occurring vanadium anion of Amanita muscaria.” J. Am. Chem. Soc. 1986, 108:11, pp. 3075-3077. Vorlage:Cite doi.
- ↑ a b c Hubregtse, T.; Neeleman, E.; Maschmeyer, T.; Sheldon, R.A.;, Hanefeld, U.; Arends, I.W.C.E. “The first enantioselective synthesis of the amavadin ligand and its complexation to vanadium.” J. of Inorg. Biochem. 2005, 99, pp. 1264-1267. Vorlage:Cite doi.
- ↑ Fu, S-C.J.; Birnbaum, S.M.; Greenstein, J.P. “Influence of Optically Active Acyl Groups on the Enzymatic Hydrolysis of N-Acylated-L-amino Acids.” J. Am. Chem. Soc. 1954, 76:23, pp. 6054-6058. Vorlage:Cite doi.
- ↑ Armstrong, E.M.; Beddoes, R.L.; Calviou, L.J.; Charnock, J.M.; Collison, D.; Ertok, N.; Naismith, J.H.; Garner, C.D. “The Chemical Nature of Amavadin. J. Am. Chem. Soc. 1993, 115:2, pp. 807-808. Vorlage:Cite doi.
- ↑ Garner, C.D.; Armstrong, E.M.; Berry, R.E.; Beddoes, R.L.; Collison, D.; Cooney, J.J.A.; Ertok, S.N.; Helliwell, M. “Investigations of Amavadin.” J. of Inorg. Biochem. 2000, 80, pp. 17-20. Vorlage:Cite doi.