Sigma-Aldrich Bovine Serum Albumin. Cohn Fraction V, lyophilized powder, ≥96% (agarose gel electrophoresis). 10 g

Serum albumins are soluble constituents of the circulatory system. Bovine serum albumin (BSA) is homologous to human serum albumin (HSA). BSA consists of three homologous domains (I, II, III), that are separated into nine loops by disulfide bonds.[1] Serum albumin acts as a depot protein.[1]

Bovine Serum Albumin has been used:

• for in vitro high molecular weight (HMW)-species formation assay[2]
• for immunohistochemistry[3]
• in Escherichia coli quantitative polymerase chain reaction (qPCR) analysis[4]

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.

This is a cold alcohol fractionated albumin that is produced by Sigma-Aldrich with a stricter adherence to the original Cohn method of fractionation than other commercially available bovine albumins.