Albumin from Bovine Serum Frequently Asked Questions (FAQs)

Albumins are the most abundant protein in serum or plasma, accounting for 60% of the total protein content and have an important role in modulating osmotic pressure (fluid shifts between the vascular and tissue compartments). Unlike globulins, albumins have comparatively low molecular weights, are soluble in water, are easily crystallized, and contain an excess of acidic amino acids.

Albumins are soluble in water and can act as a transporter or carrier for many hormones and drugs that are not readily water-soluble. It binds water, Ca2+, Na+, and K+, and due to a hydrophobic cleft, also binds fatty acids, bilirubin, hormones, and drugs. Albumin is used to solubilize lipids and is also used as a blocking agent in western blots or ELISA applications. The proteins also play an important role in regulating pH.

The molecular weight of albumins varies depending on the type of albumin. The mature human albumin consists of 585 amino acids and has a molecular mass of 66 kDa.

The most well-known types of albumin proteins are human, bovine serum albumins and recombinant. Other albumins include chicken, mouse, porcine.

Bovine serum albumin (BSA) is a commonly used small (~66 kDa) globular albumin protein that binds, sequesters, and stabilizes a range of important molecules and proteins. It is broadly used as an additive to cell culture media, especially serum-free media, and provides a range of benefits including protection from oxidative damage and stabilization of other media components such as fatty acids and pyridoxal.

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.

Albumin is synthesized in the liver by hepatocytes and then is rapidly excreted into the blood stream, with very little albumin stored in the liver. Albumins serve as a modulator of plasma oncotic pressure in human and can transport both endogenous and exogenous ligands, such as drugs. In clinical medicine, human serum albumin is measured as a marker for the nutritional status of an individual patient.

The amino acid sequence and structure of human albumin have been determined. Human albumin is a protein with no carbohydrate content. It is a single polypeptide chain with one free sulfhydryl group on residue # 34 and 17 intrachain disulfide bonds.

BSA contains about 583 amin acid residues and does not have carbohydrates within a single polypeptide chain. It contains 17 interchain disulfide bridges and 1 sulfhydryl group at pH 5-7.

Albumin levels in the blood can be used to diagnose a variety of medical conditions, including liver disease, kidney disease, and malnutrition. Low levels of albumin in the blood can indicate liver or kidney damage, while high levels can indicate dehydration.

Albumins are commonly used in the laboratory as a blocking agent to prevent non-specific binding in immunoassays. They can also be used as a stabilizer in enzyme assays and as a protein standard in protein quantification assays.

• Western blotting: BSA is commonly used as a blocking agent in Western blotting to prevent non-specific binding of primary and secondary antibodies to the membrane.
• ELISA (enzyme-linked immunosorbent assay): BSA can be used as a blocking agent in ELISA to prevent non-specific binding of antibodies to the plate.
• Cell culture: Albumin is commonly used as a supplement in cell culture media to provide cells with essential nutrients and growth factors.
• Stabilizer: Albumin can be used as a stabilizer in vaccines, pharmaceuticals, and other biological products to protect against degradation.

Albumins are responsible for maintaining the osmotic pressure of the blood by preventing the loss of water from the bloodstream. They do this by attracting water molecules through their polar and charged amino acid residues.

Albumins purified from a variety of methods including the true Cohn fractionation method, heat shock, chromatography, and modified ethanol fractionation methods. Additional purification steps may include charcoal filtration and crystallization.

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.

Yes, albumins can be denatured by changes in pH, temperature, and ionic strength. Denaturation can cause the protein to lose its functional properties.

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.

Albumins can bind to a variety of molecules, including fatty acids, hormones, and drugs. They do this through hydrophobic and electrostatic interactions.