Bovine serum albumin
From DrugPedia: A Wikipedia for Drug discovery
Bovine serum albumin
Bovine serum albumin (also known as BSA or "Fraction V") is a serum albumin protein that has numerous biochemical applications including ELISAs (Enzyme-Linked Immunosorbent Assay), immunoblots, and immunohistochemistry. It is also used as a nutrient in cell and microbial culture. In restriction digests, BSA is used to stabilize some enzymes during digestion of DNA and to prevent adhesion of the enzyme to reaction tubes and other vessels. This protein does not affect other enzymes that do not need it for stabilization. BSA is also commonly used to determine the quantity of other proteins, by comparing an unknown quantity of protein to known amounts of BSA. BSA is used because of its stability, its lack of effect in many biochemical reactions, and its low cost since large quantities of it can be readily purified from bovine blood, a byproduct of the cattle industry. The nickname "Fraction V" refers to albumin being the fifth fraction of the original Edwin Cohn purification methodology that made use of differential solubility characteristics of plasma proteins. By manipulating solvent concentrations, pH, salt levels, and temperature, Cohn was able to pull out successive "fractions" of blood plasma. The process was first commercialized with human albumin for medical use and later adopted for production of BSA.
Properties
PHYSICAL PROPERTIES of BSA: Number of residues: 607 Molecular weight: 66382 Da pH in water at 25 °C: 4.7 Optical absorbance of 1 g/l at 279nm0. Dimensions: 40x40x140 cubic angstroms An 18-residue signal peptide is cut off from the precursor protein upon secretion, hence the precursor has 607 amino acid residues and a molecular weight of 66.4 kDa.
Function
Bovine serum albumin has been given little attention in respect to its role in the functional properties of whey protein concentrates, and makes up only about 5% of the protein in whey protein concentrates. Its primary biological function has been associated with its lipid binding properties (Fox and Flynn, 1992), but the mechanism of this role has not been clearly elucidated. It may play a role in mediating lipid oxidation, since BSA has been shown invitro to protect lipids against phenolic induced oxidation (Smith, et al., 1992; Koizumi and Nonaka, 1975). Strand (1995) claimed that denatured BSA might “reduce the probability of a person acquiring certain diseases, such as insulin dependent diabetes or auto-immune disease." Bosselears, et al. (1994) compared the anti-mutagenic effect of BSA, soy protein, total whey protein, b-lactoglobulin and pepsin-hydrolysed casein. Of these proteins, only the enzyme-hydrolysed casein and BSA were effective against genotoxic compounds. Bovine serum albumin has been used as a component of cell media to regenerate plants from cultured guard cells (Tallman and Malibu, 1996) and to provide for enhancement of production of plasminogen activator.
