10297. Mistletoe Lectins

Description and references

Toxic glycoproteins isolated from European mistletoe, Viscum album L., Viscaceae, and related species. Type II ribosome inactivating proteins, similar to ricin, q.v.; inhibit protein synthesis and induce apoptosis. Comprised of 2 polypeptide chains, the cytotoxic A chain is linked to the carbohydrate-binding B chain via a disulfide bridge. Three isoforms have been identified that differ in carbohydrate binding specificity. Isoln of ML-I: P. Ziska et al., Experientia 34, 123 (1978); P. Luther et al., Int. J. Biochem. 11, 429 (1980) DOI PubMed; S. Olsnes et al., J. Biol. Chem. 257, 13263 (1982) PubMed; of I, II and III: H. Franz et al., Biochem. J. 195, 481 (1981) PubMed. Characterization and bioactivities: eidem, Oncology 43, Suppl. 1, 22 (1986) PubMed. Amino acid sequence of ML-I A chain: M. H. Soler et al., FEBS Lett. 399, 153 (1996) DOI PubMed; of B chain: idem et al., Biochem. Biophys. Res. Commun. 246, 596 (1998) DOI PubMed. Crystal structure of ML-I: R. Krauspenhaar et al., ibid. 257, 418 (1999) DOI PubMed. Structure of ML-III A chain: R. Wacker et al., J. Pept. Sci. 10, 138 (2004) DOI PubMed; of B chain: idem et al., ibid. 11, 289 (2005) DOI PubMed. Review of cytotoxic and immunostimulant activities: T. Hajtó et al., Evid. Based Complement. Altern. Med. 2, 59-67 (2005) DOI PubMed.

Derivative

Mistletoe Lectin I.

Nomenclature

ML-I; Viscum album agglutinin I; VAA-I; viscumin.

Properties

Mol wt 66 kDa; also exists as a dimer in soln, mol wt 115 kDa. Mol wt of A chain, 29 kDa; of B chain, 34 kDa. Carbohydrate specificity: sialic acid and d-galactose. Isoelectric point: pH 6.1. Sol in phosphate buffered saline. LD50 i.p. in mice: 28 μg/kg (Franz, 1986).

Derivative

Mistletoe Lectin II.

Nomenclature

ML-II.

Properties

Mol wt 60 kDa. Mol wt of A chain, 27 kDa; of B chain, 32 kDa. Carbohydrate specificity: d-galactose and N-acetyl-d-galactosamine. LD50 i.p. in mice: 1.5 μg/kg (Franz, 1986).

Derivative

Mistletoe Lectin III.

Nomenclature

ML-III.

Properties

Mol wt 50 kDa. Mol wt of A chain, 25 kDa; of B chain, 30 kDa. Carbohydrate specificity: N-acetyl-d-galactosamine. LD50 i.p. in mice: 55 μg/kg (Franz, 1986).

Derivative

Aviscumine.

Nomenclature

CAS number: 223577-45-5
Toxin ML-I (mistletoe lectin I) (Viscum album); rML-I.

Description and references

Nonglycosylated ML-I produced by recombinant technology in E. coli. mol wt 57 kDa. Cloning and characterization: J. Eck et al., Eur. J. Biochem. 264, 775 (1999) DOI PubMed; idem et al., ibid. 265, 788 (1999) DOI PubMed. Determn in plasma by immuno-polymerase chain reaction (IPCR) assay: M. Adler et al., J. Pharm. Biomed. Anal. 39, 972 (2005) DOI PubMed. Clinical pharmacology in patients with solid tumors: P. Schffski et al., Eur. J. Cancer 41, 1431 (2005) DOI PubMed.