Amavadin

Amavadin
Names
IUPAC name
bis[N-[(1S)-1-(carboxy-κO)ethyl]-N-(hydroxy-κO)-L-alaninato(2-)-.κN,κO]-vanadium
Identifiers
12705-99-6 YesY
Properties
[V{NO[CH(CH3)CO2]2}2]2−
Molar mass 398.94 g/mol
Appearance Light blue in solution
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Amanita muscaria contains 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 + 4 H+

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.

Amavadin is a C2-symmetric anion with a 2− charge. The twofold 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 ligand precursor found in amavadin (left), the ligand (center), and H3 (HIDA, right).

Biological function

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

  1. 1 2 3 4 Berry, R.E.; Armstrong, E.M.; Beddoes, R.L.; Collison, D.; Ertok, S.N.; Helliwell, M.; Garner, C.D. (1999). "The Structural Characterization of Amavadin". Angew. Chem. Int. Ed. 38 (6): 795–797. doi:10.1002/(SICI)1521-3773(19990315)38:6<795::AID-ANIE795>3.0.CO;2-7.
  2. ↑ 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. Kneifel, H.; Bayer, E. (1986). "Stereochemistry and total synthesis of amavadin, the naturally occurring vanadium compound of Amanita muscaria". Journal of the American Chemical Society. 108 (11): 3075–3077. doi:10.1021/ja00271a043..
  3. 1 2 3 Hubregtse, T.; Neeleman, E.; Maschmeyer, T.; Sheldon, R.A.; Hanefeld, U.; Arends, I.W.C.E. (2005). "The first enantioselective synthesis of the amavadin ligand and its complexation to vanadium". J. Of Inorg. Biochem. 99 (5): 1264–1267. doi:10.1016/j.jinorgbio.2005.02.004. PMID 15833352.
  4. ↑ Fu, S-C.J.; Birnbaum, S.M.; Greenstein, J.P. (1954). "Influence of Optically Active Acyl Groups on the Enzymatic Hydrolysis of N-Acylated-L-amino Acids". J. Am. Chem. Soc. 76 (23): 6054–6058. doi:10.1021/ja01652a057.
  5. ↑ Armstrong, E.M.; Beddoes, R.L.; Calviou, L.J.; Charnock, J.M.; Collison, D.; Ertok, N.; Naismith, J.H.; Garner, C.D. (1993). "The Chemical Nature of Amavadin". J. Am. Chem. Soc. 115 (2): 807–808. doi:10.1021/ja00055a073.
  6. ↑ Garner, C.D.; Armstrong, E.M.; Berry, R.E.; Beddoes, R.L.; Collison, D.; Cooney, J.J.A.; Ertok, S.N.; Helliwell, M. (2000). "Investigations of Amavadin". J. Of Inorg. Biochem. 80 (1–2): 17–20. doi:10.1016/S0162-0134(00)00034-9. PMID 10885458.
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