Bovine Serum Albumin

Bovine Serum Albumin (BSA) is a globular, non-glycosylated α-helical plasma protein produced in the bovine liver. It consists of three domains (I, II, and III), each with two sub-domains (A and B), arranged in a heart-shaped structure.

Bovine serum albumin has been used-

• along with BTS (Beltsville thawing solution), for the extension of sperms during sperm motion analysis
• as a component of modified Krebs-Ringer buffer (dmKRBT)
• in gel shift analysis
• as a blocking agent in immunocytochemistry, immunohistochemistry,(4) immunofluorescence protocol and sandwich enzyme-linked immunosorbent assay (ELISA)
• as a component of phosphate buffer saline (PBS) solution to resuspend cells for analysis during flow cytometry
• as a protein standard to quantify proteins in tissue samples via Bradford’s method
• to measure the enzyme activity of 17β HSD enzyme

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

Often referred to as Cohn fraction V; this product is prepared by a modified method of the Cohn cold ethanol fractionation method.

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.