Bovine Serum Albumin

Bovine Serum Albumin (BSA) is a plasma protein produced in the bovine liver that has a globular, non-glycosylated α-helical structure. It consists of a single polypeptide chain with 583 amino acid residues and 17 cysteine residues that form the cross-linked disulfide bridges, stabilizing its structure. The BSA protein comprises three structurally distinct domains (I, II, and III), each of which contains two sub-domains (A and B) arranged in a heart-shaped architecture.

Bovine Serum Albumin (BSA) has been used

• as a component of phosphate buffer saline (PBS) solution for dissolving tumor necrosis factor α (TNFα), which was added as a supplement for culture media
• as a blocking agent to reduce non-specific binding during the albumin sensor assay
• as a blocking agent in the immunofluorescence (IF) assay
• as a protein standard in the Bradford assay

Bovine Serum Albumin (BSA) is a versatile protein commonly utilized in cell and tissue culture media as a supplement. It helps in lipid solubilization and stabilizing other proteins. BSA is also a carrier for small molecules such as steroids, fatty acids, and thyroid hormones. It serves as a standard protein for immunochemical tests to determine protein concentration in a solution and calibration studies.

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

This BSA product for molecular biology is tested for the following properties:
* Alkaline Phosphatase-free
* DNase-free / Exonuclease-free
* Nickase-free / Endonuclease-free
* Peroxidase-free
* Protease-free
* RNase-free

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.