Bovine Serum Albumin

Bovine serum albumin (BSA) is a 66.4kDa, water-soluble protein. It has a single polypeptide chain consisting of about 583 amino acid residues and no carbohydrates. BSA possesses three homologous domains formed by six a-helices. Depending on pH, it undergoes reversible conformational isomerization. The native structure of the protein becomes reactive and flexible on heating.

Bovine serum albumin (BSA) has been used:

• as a standard in Bradford protein assay method for protein quantification
• to study the formation of multiligand complex of BSA with retinol, resveratrol and (-)-epigallocatechin-3-gallate (EGCG)
• to study the adsorption of BSA by biochar (charcoal produced from plant matter)

Bovine serum albumin (BSA) has been used as a model protein in various studies, such as immunodiagnostic procedures, cell culture media and clinical chemistry.

Certain conformational and primary-sequence epitopes of BSA are suspected allergens in human beef and milk allergies.

Serum albumin may be referred to as Fraction V. This naming convention is taken from the original Cohn method of fractionating serum proteins using cold ethanol precipitation. Serum albumin was found in the fifth ethanol fraction using Cohn′s method. Since then, the term "Fraction V" has been used by some to describe serum albumin regardless of the method of preparation. Others have used this term to describe serum albumin purified by ethanol fractionation methods that have been highly modified since the original Cohn method was described. Sigma-Aldrich manufactures and distributes serum albumins purified from a variety of primary methods including the true Cohn fractionation method, modified ethanol fractionation methods, heat shock and chromatography. Additional purification steps may include crystallization or charcoal filtration.

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