Imject™ cBSA (in PBS) (Thermo Scientific™)

Thermo Scientific Imject Cationized Bovine Serum Albumin (cBSA) functions as an easy-to-use and highly immunogenic carrier protein for preparing antigens for use in antibody production.

Imject cBSA is prepared by modifying native BSA with excess ethylenediamine, essentially capping all negatively-charged carboxyl groups with positively-charged primary amines. The result is a highly positively-charged protein (pI > 11) that has significantly increased immunogenicity compared to native BSA. In addition, the increased number of primary amines provides for a greater number of antigen molecules to be conjugated with typical crosslinking methods. Imject cBSA is an excellent choice for immunogen preparation when greater immunogenicity is needed relative to BSA but conditions are not amenable to using keyhole limpet hemocyanin (KLH) or Blue Carrier Protein.

Features of the Imject Cationized Bovine Serum Albumin:

• Purified bovine serum albumin (BSA) that is cationized and supplied lyophilized in PBS
• Single polypeptide protein with molecular mass > 67,000 Daltons
• Contains 59 lysine residues, plus numerous other primary amines added by cationization, most of which are capable of reacting with a conjugation reagent to attach antigens
• Net positive charge (pI >11), conferring solubility in conditions not suitable for the negatively-charged native BSA (pI 5.1)
• Significantly greater immunogenicity than native BSA because the positively charged protein is processed differently by the immune-response system (see references).

Carrier proteins are large, complex molecules capable of stimulating an immune response upon injection. Successful production of antibodies specific to small antigens (i.e., peptides or drug compounds) requires that these haptens be covalently conjugated to a larger, more complex molecule (usually a protein) to make them immunogenic. Carrier proteins are chosen based on immunogenicity, solubility, and whether adequate conjugation with the carrier can be achieved. Imject Cationized BSA (cBSA), which was previously called “SuperCarrier Protein” is very soluble in aqueous buffers and contains numerous primary amines that can be targeted for conjugation with glutaraldehyde, EDC, and other crosslinking reagents. For sulfhydryl-target conjugation (e.g., cysteine-containing peptide antigens), use Imject Maleimide-Activated cBSA.

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