10301. Viscotoxin

Nomenclature

CAS number: 76822-96-3

Description and references

Mixture of amphipathic, highly basic, cysteine-rich, toxic polypeptides isolated from European mistletoe, Viscum album L., Viscaceae. Structurally classified with the thionin family of plant proteins. Several isoforms are known, containing 46 amino acid residues and 3 disulfide bridges. Viscotoxin A3 is the most abundant and cytotoxic. Viscotoxins interact with cell membranes, leading to permeabilization and cell death. Similar peptides, phoratoxins, have been isolated from American mistletoe, Phoradendron leucarpum, Viscaceae. Isoln of crude viscotoxin: K. Winterfeld, L. H. Bijl, Ann. 561, 107 (1948). Improved isoln method: G. Samuelsson, Sven. Farm. Tidskr. 65, 481 (1961) PubMed. Separation of components: idem, Acta Chem. Scand. 20, 1546 (1966). Purification and comparison of cytotoxicity in Yoshida sarcoma cells: G. Schaller et al., Phytother. Res. 10, 473 (1996) DOI. Comparison of sequences and 3-D structure of A3: S. Romagnoli et al., Biochem. J. 350, 569 (2000) DOI PubMed. Mechanism of action studies: A. Coulon et al., Biochim. Biophys. Acta 1559, 145 (2002) DOI PubMed; M. Giudici et al., FEBS J. 273, 72 (2006) DOI PubMed.

Chemical structure

Properties

LD50 of partially purified viscotoxin A (mg/kg): 0.78 ±0.07 i.p. in mice (Samuelsson, 1961).

Derivative

Viscotoxin A1.

Nomenclature

CAS number: 198228-20-5
C200H330N62O68S6; mol wt 4883.52.
C 49.19%, H 6.81%, N 17.78%, O 22.28%, S 3.94%.

Description and references

Amino acid sequence: S. Orru et al., Biol. Chem. 378, 989 (1997) PubMed.

Derivative

Viscotoxin A2.

Nomenclature

CAS number: 54651-39-7
C199H318N62O66S6; mol wt 4827.42.
C 49.51%, H 6.64%, N 17.99%, O 21.87%, S 3.99%.

Description and references

Amino acid sequence: T. Olson, G. Samuelsson, Acta Chem. Scand. 26, 585 (1972) PubMed.

Derivative

Viscotoxin A3.

Nomenclature

CAS number: 55465-79-7
C201H328N62O64S6; mol wt 4829.52.
C 49.99%, H 6.85%, N 17.98%, O 21.20%, S 3.98%.

Description and references

Amino acid sequence: G. Samuelsson et al., Acta Chem. Scand. 22, 2624 (1968) PubMed.

Derivative

Viscotoxin B.

Nomenclature

CAS number: 11088-20-3
C197H328N64O67S6; mol wt 4857.49.
C 48.71%, H 6.81%, N 18.45%, O 22.07%, S 3.96%.

Description and references

Amino acid sequence: G. Samuelsson, B. M. Pettersson, Eur. J. Biochem. 21, 86 (1971) DOI PubMed.