Bovine Serum Albumin

Bovine serum albumin (BSA) is an α-helical, globular and non-glycosylated 66kDa protein. It is characterized with three domains with two subdomains under each. BSA belongs to the serum albumins family and has 17-disulfide bonds.

The most abundant plasma protein in mammals is albumin. It is produced in the liver and transferred as a non-glycosylated protein into the plasma. This multifunctional protein has an amazing ability to bind to ligands.

Bovine Serum Albumin has been used as a component of Tris-buffered saline (TBST) to stabilize polyvinylidene fluoride (PVDF) membranes during western blotting. It has also been used in along with phosphate-buffered saline with tween detergent (PBST) as a blocking buffer in enzyme linked immunosorbent assay(ELISA).

Bovine serum albumin (BSA) is extensively used for drug delivery since it is widely available, cheap and easily purified, has ligand-binding properties, and is widely accepted in the pharmaceutical industry.

Albumin is the most important circulatory protein involved in the control of Ca²⁺ (and Mg²⁺) levels in mammals.

Bovine Serum Albumin (BSA) is a transporter for drugs, hormones and fatty acids. It is used as a blocking agent in enzyme linked immunosorbent assay (ELISA) for preventing non-specific binding of antigens and antibodies to the microtiter plates. BSA is a crucial component of the cell culture media and favors embryonic stem cells (hESC) differentiation. BSA shares structural features with human serum albumin. Its high solubility, low cost and purity and interaction with surfactant is exploited in cosmetic and pharmaceutical industry.

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.