Antifreeze peptide SS-3

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• Material Safety Data Sheets (MSDS)

Batch to batch variation of the purity

Antifreeze peptide SS-3 is a 33-amino-acid polypeptide isolated from the shorthorn sculpin (Myoxocephalus scorpius). It is one of two major antifreeze polypeptides found in this species, the other being SS-8, which contains 45 residues. The N-terminal methionyl residue of SS-3 is blocked. When aligned for maximum structural similarity with SS-8, SS-3 exhibits 80% homology and shows a deletion of 12 amino acid residues at its N-terminal portion. Like the winter flounder antifreeze polypeptides, SS-3 contains 11-amino-acid repeat sequences. Its secondary structure is primarily alpha-helical, as determined by circular dichroic spectral data, with a helical content of approximately 45%, which is moderate compared to the 73% helical content of SS-8.

The antifreeze activity of SS-3 is relatively weak compared to that of SS-8. The 11-amino-acid repeating structures present in SS-3 are analogous to those found in SS-8 and in flounder antifreeze peptides, and are considered a conserved structural feature related to the functional domain for ice-binding. SS-3 consists of two main repeating structures. The reduction in both helical content and activity in SS-3, as well as in smaller cleavage fragments, suggests that the extent of alpha-helix and the presence of multiple repeating sequences are important for the structural integrity and ice-binding function of these polypeptides.

• Hew CL, Joshi S, Wang NC, Kao MH, Ananthanarayanan VS. Structures of shorthorn sculpin antifreeze polypeptides. Eur J Biochem. 1985;151(1):167-72.

Trifluoroacetic acid (TFA) is a common counterion from the purification process using High-Performance Liquid Chromatography (HPLC). The presence of TFA can affect the peptide's net weight, appearance, and solubility.

Impact on Net Weight: The TFA salt contributes to the total mass of the product. In most cases, the peptide content constitutes >80% of the total weight, with TFA accounting for the remainder.

Solubility: TFA salts generally enhance the solubility of peptides in aqueous solutions.

In Biological Assays: For most standard in vitro assays, the residual TFA levels do not cause interference. However, for highly sensitive cellular or biochemical studies, please be aware of its presence.