Albumins bind, sequester and stabilize a range of important molecules and proteins. Bovine serum albumin (BSA) is a small (~66 kDa) globular albumin protein that has been utilized in many well-cited applications. Our BSA products have been used and published in peer-reviewed articles for many applications, including cell culture, IHC, ELISA and many more. We offer a wide variety of BSA products for your research and manufacturing needs
The table below shows common applications and peer-reviewed articles that use our most popular BSA products. The list is not intended to be comprehensive and product numbers not listed may be suitable and specifically tested for various uses. Select the BSA best suited for your needs by reviewing what other researchers just like you are using.
Purification Methods and Application References for Bovine Serum Albumin
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.
Albumins are a group of acidic proteins which occur plentifully in the body fluids and tissues of mammals and in some plant seeds. Unlike globulins, albumins have comparatively low molecular weights, are soluble in water, are easily crystallized, and contain an excess of acidic amino acids. Serum and plasma albumin are carbohydrate-free and comprises 55-62% of the protein present.
Albumin binds water, Ca2+, Na+, and K+. Due to a hydrophobic cleft, albumin binds fatty acids, bilirubin, hormones, and drugs. The main biological function of albumin is to regulate the colloidal osmotic pressure of blood. Human and bovine albumins contain 16% nitrogen and are often used as standards in protein calibration studies. Albumin is used to solubilize lipids and is also used as a blocking agent in western blots or ELISA applications. Globulin free albumins are suitable for use in applications where no other proteins should be present (e.g., electrophoresis).
Albumins are readily soluble in water and can only be precipitated by high concentrations of neutral salts such as ammonium sulfate. The solution stability of BSA is very good (especially if the solutions are stored as frozen aliquots). In fact, albumins are frequently used as stabilizers for other solubilized proteins (e.g., labile enzymes). However, albumin is readily coagulated by heat. When heated to 50 °C or above, albumin quite rapidly forms hydrophobic aggregates which do not revert to monomers upon cooling. At somewhat lower temperatures aggregation is also expected to occur, but at relatively slower rates.
Albumin is relatively simple to isolate and purify. One of the first methods of isolation involved extensive dialysis of serum against water and removed most globulins. A second procedure took advantage of the good solubility of albumin at low to moderate ammonium sulfate concentrations, and effected precipitation by lowering the pH. Electrophoretic isolation was also employed, as was affinity chromatography. However, none of these methods were applicable to large scale production.
Initial isolation is accomplished by heat treatment or by alcohol precipitation. Most commercial preparations are now prepared by alcohol precipitation, a method developed by E. J. Cohn and his associates in the 1940's ("Fraction V" yields albumin with a purity of about 96%), or by Heat Treatment. The additional removal of impurities can be accomplished by crystallization, preparative electrophoresis, ion exchange chromatography, affinity chromatography (e.g., ConA-agarose removes glycoproteins), heat treatment (removes globulins), low pH treatment, charcoal treatment, organic solvent precipitation (i.e., isooctane), and low temperature treatment. Charcoal treatment and organic solvent precipitation remove fatty acids.