BSA is also commonly used to determine the quantity of other proteins, by comparing an unknown quantity of protein to known amounts of BSA (see Bradford protein assay). This protein does not affect other enzymes that do not need it for stabilization. In restriction digests, BSA is used to stabilize some enzymes during the digestion of DNA and to prevent adhesion of the enzyme to reaction tubes, pipette tips, and other vessels. BSA is also used as a nutrient in cell and microbial culture. During this process, minimization of nonspecific binding of antibodies is essential in order to acquire the highest signal to noise ratio. The BSA blocker improves sensitivity by decreasing background noise as the sites are covered with the moderately non-reactive protein. This binding of BSA to nonspecific binding sites increases the chance that the antibodies will bind only to the antigens of interest. During immunohistochemistry, which is the process that uses antibodies to identify antigens in cells, tissue sections are often incubated with BSA blockers to bind nonspecific binding sites. Because BSA is a small, stable, moderately non-reactive protein, it is often used as a blocker in immunohistochemistry. īSA has numerous biochemical applications including ELISAs (Enzyme-Linked Immunosorbent Assay), immunoblots, and immunohistochemistry. Applications īSA is often used a model for other serum albumin proteins, especially human serum albumin, to which it is 76% structurally homologous. BSA can also bind other substances such as salicylate, sulfonamides, bilirubin, and other drugs, which bind to “site 1” in subdomain IIA, while tryptophan, thyroxine, octanoate and other drugs that are aromatic in nature bind to “site 2” in subdomain IIIA. There are approximately 6 different long chain fatty acid binding sites on the protein, the three strongest of which are located one per each domain. Mean residue ellipticity: 21.1 209 nm 20.1 222 nm īSA, like other serum albumins, is critical in providing oncotic pressure within capillaries, transporting fatty acids, bilirubin, minerals and hormones, and functioning as both an anticoagulant and an antioxidant.Dimensions: 140 × 40 × 40 Å (prolate ellipsoid where a = b Extinction coefficient of 43,824 M −1cm −1 at 279 nm.isoelectric point in water at 25 ☌: 4.7.The domains, named I, II, and III, are broken down into two sub-domains, A and B. īSA has three homologous but structurally different domains. An additional six amino acids are cleaved to yield the mature BSA protein that contains 583 amino acids. An N-terminal 18-residue signal peptide is cut off from the precursor protein upon secretion, hence the initial protein product contains 589 amino acid residues. The full-length BSA precursor polypeptide is 607 amino acids (AAs) in length. Lyophilized Bovine Serum Albumin Properties The process was first commercialized with human albumin for medical use and later adopted for production of BSA. By manipulating solvent concentrations, pH, salt levels, and temperature, Cohn was able to pull out successive "fractions" of blood plasma. 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. It is often used as a protein concentration standard in lab experiments. albuminīovine serum albumin ( BSA or "Fraction V") is a serum albumin protein derived from cows. For the family of mammalian albumins, see serum albumin. For the human variant, see human serum albumin. This article is about albumin specific to cows.
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