An Homogeneous Protein

    Bovine serum albumin (BSA) is one of the most commonly used carriers for conjugation in antibody production. It belongs to the class of serum proteins called albumins, which make up about half of the protein in plasma and are the most stable and soluble proteins in plasma. It is very popular with laboratories developing immunoassays, mostly due to its availability, solubility and the numerous functional groups present for coupling to heptans.

Molecular Weight

    Molecular weight (MW): The MW of BSA is 67 X 10³ which is much smaller than that of KLH, another commonly used carrier protein. It is, however, much more soluble and is immunogenic. It contains 59 lysines, and 30-35 of these are primary amines capable of reacting with a conjugation sites of linkers. It is a popular carrier for weakly antigenic compounds.

Solubility

    Solubility in aqueous solution: BSA is easily dissolved in an aqueous solution. It can be highly purified to become homogeneous. BSA is commonly used as protein standard in protein assays and as a molecular weight standard for SDS-PAGE and gel permeation chromatography.

Applications

    BSA can be used to block nonspecific binding sites in many immunochemical experiments such as ELISA, immunoblotting and immunohistochemical studies. It may be used as a non-relevant protein in enzyme immunoassays; KLH cannot be used for this because the anti-KLH antibodies, which formed during immunization, will interfere with the measurement of anti-heptan antibodies. When KLH is used as the carrier, heptan-BSA conjugates can be used because they do not interfere with the measurement for anti-heptan antibodies.

 

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