Toxin single-chain types

The methods described below for the preparation of antibody-toxin conjugates containing A chains isolated from toxins or single-chain RIPs are generally applicable to the synthesis of conjugates using any type of antibody and all known RIPs of plant origin. 

Ricin is a type II toxin. The A chain (ricin A) contains 267 amino acid residues, and the B chain (ricin B) 262 residues. Ricin A is exceptionally toxic, and it has been estimated that a single molecule is sufficient to kill an individual cell. This peptide can be prepared by genetic engineering using Escherichia coli. The potent action of this material on eukaryotic cells has been investigated in anticancer therapy. Ricin A has been coupled to monoclonal antibodies and successfully delivered specifically to the tumour cells. However, in vitro toxicity of ricin A-based immunotoxins is enhanced significantly if ricin B is also present. 

BotuNsm toxin, botulin (botulinum toxin). Botulism is today a very infrequently occurring form of food poisoning by B., a metabolite of Clostridium botulinum. This rod-like bacterium develops anaerobically in conserved meat products, occasionally also in conserved vegetable or fish products as a result of an inadequate addition of salt or (in case of fish) of inadequate acidification. B. consists of a single polypeptide chain with a molecular mass of ca. 150000.7 types of... 

Anticholinesterase-type neurotoxin has 57-60 amino acids in a single polypeptide chain, cross-linked by three disulfide bonds. The two-dimensional structure of fasciculin 2 from dendroaspis venom is shown in Fig. 15. Fasciculin 2 is identical with toxin F7 isolated by Viljoen and Botes (1973). Similarly, toxins C and D from D. polylepis polylepis venom... 

---