Monday, August 30, 2010

Toxin Conjugates

Toxin
Bio Synthesis extensive experience in peptide and oligonucleotide synthesis coupled to its work over the past years in the glycosides area would allow its staff to design the best compound to satisfy your needs as well as its effective preparation.

Toxin Conjugates
These conjugates consist of one of the several naturally occurring toxic peptides or proteins, e.g. ricin, cholera toxin and cone snail neurotoxin, cross-linked to a ligand, e.g. peptide, protein, oligonucleotide, oligosaccharide or their analogs, that specifically bind to certain cell receptors. Thus, the role of the ligand is to largely target the delivery of the toxin to those cells that express a specific receptor, while that of the toxin moiety is to interact with specific enzymes or cellular receptors and interfere with their normal functions.

Conjugation of Toxins with Peptide Ligands
Toxins can be conjugated to peptide ligands, such as peptide hormones, (somatostatin and bombesin), tumor-homing peptides or to proteins via a spacer which can have a disulfide bond that can be cleaved by reducing agents. The flexibility of the spacer can affect the toxin performance having a higher activity when linked by more flexible spacers. In some cases the toxins can be linked to certain antigen-specific antibodies to yield immunotoxins that are conjugates with significant potential in cancer therapy.

Conjugation of Toxins with Oligonucleotides
In this case, the toxin is conjugated to an ODN sequence called an aptamer. Aptamers, like antibodies, can provide specific molecular recognition that is useful for diagnostic and therapeutic purposes. The methodology used to produce toxin-aptamer conjugates is in several aspects similar to that used to produce ODN-peptide conjugates.

Conjugation of Toxins with Oligosaccharides
Another family of compounds to which toxins can be conjugated is oligosaccharides. At the present the main application of oligosaccharide-toxin conjugates is the vaccine area to elicit an immune response against the oligosaccharide moiety of the conjugate. Different from peptide and oligonucleotide conjugates and in order to stimulate the correct immune response the structural requirements for linking of the oligosaccharide to the toxin are more stringent. Thus, this type of conjugations would require chemical procedures designed to satisfy those structural requirements.

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