Merck, A3156-5G, Bovine Serum Albumin

General description
BSA is a single polypeptide chain consisting of about 583 amino acid residues and no carbohydrates. At pH 5-7 it contains 17 intrachain disulfide bridges and 1 sulfhydryl group.
Bovine serum albumin (BSA) is a 66 kDa protein consisting of three domains with two subdomains under each. It is a α-helical, globular and non-glycosylated protein. Albumin is the most abundant plasma protein in humans.
Application
Bovine serum albumin has been used:
to prevent sticking of the chromosome to the glass micropipette for elasticity measurements using aspiration
to block lung homogenates in the plate for mucin protein enzyme-linked immunosorbent assay
in alginate solution as a protein model for drug release kinetics investigation

Biochem/physiol Actions
Bovine serum albumin is broadly used as an additive to cell culture media, especially serum-free media. It provides a range of benefits including protection from oxidative damage and stabilization of other media components such as fatty acids and pyridoxal.
Certain conformational and primary-sequence epitopes of BSA are suspected allergens in human beef and milk allergies.
Bovine Serum Albumin (BSA) is a transporter for drugs, hormones and fatty acids. Albumin turnover is seen in infants with iron deficiency anemia. BSA acts as a vital constituent in the cell culture media and favors human embryonic stem cells (hESC) differentiation.
Preparation Note
Purified by a combination of heat shock and ethanol fractionation
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.