Merck, A3912-50G, Bovine Serum Albumin

General description
Bovine serum albumin (BSA) is a 66.4 kDa, water-soluble protein composed of 583 amino acids. It has a single polypeptide chain with three homologous domains formed by six α-helices. Depending on pH, it undergoes reversible conformational isomerization. The native structure of the protein becomes reactive and flexible on heating. BSA has been used as a model protein in various applications, including immunodiagnostic procedures, cell culture media and clinical chemistry. Serum albumins facilitates drug disposition and efficacy by maintaining osmotic blood pressure.
Application
Bovine Serum Albumin (BSA) has been used:
to study its adsorption on a planar poly(acrylic acid) (PAA) brush layer through fixed-angle optical reflectometry
to measure its adsorption on a variety of thin films by means of total internal reflection spectroscopy
as a constituent of Krebs-Ringer bicarbonate buffer, which acts as a perfusate during placental perfusion

Biochem/physiol Actions
Certain conformational and primary-sequence epitopes of BSA are suspected allergens in human beef and milk allergies.
Preparation Note
Prepared using heat shock 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.
Analysis Note
Remainder mostly globulins.