User:KNoelA/Bovine serum albumin

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This article is about albumin specific to cows. For the human variant, see human serum albumin. For the family of mammalian albumins, see serum albumin.

Bovine serum albumin (BSA or "Fraction V") is a serum albumin protein derived from cows. It is often used as a protein concentration standard in lab experiments.

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. BSA is commonly used as a model in medical experiments because it resembles HSA. The interaction between biomedical alloys and BSA has been studied to provide more successful and safe implantation of medical devices. Serum albumins can be allergens. There is a high degree of conservation between serum albumins (SA). [1] BSA is present in beef and cow's milk.

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Properties[edit]

The full-length BSA precursor protein is 607 amino acids (AAs) in length. 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. An additional six amino acids are cleaved to yield the mature BSA protein that contains 585 amino acids. BSA is a heart shaped protein that consists of a polypeptide folded into 3 α-helical domains. Albumin commonly bonds to ligands and metal alloys. Albumins have the ability to transport ligands due to their flexible conformation. Physical properties of BSA:


 * Number of amino acid residues: 585
 * Molecular weight: 66,463 Da    (= 66.5 kDa)
 * isoelectric point in water at 25 °C: 4.7
 * Extinction coefficient of 43,824 M−1cm−1    at 279 nm
 * Dimensions: 140 × 40 × 40 Å (prolate ellipsoid where a    = b < c)
 * pH of 1% Solution: 5.2-7
 * Optical Rotation: [α]259: -61°; [α]264:    -63°
 * Stokes Radius (rs): 3.48 nm
 * Sedimentation constant, S20,W × 1013:    4.5 (monomer), 6.7 (dimer)
 * Diffusion constant, D20,W × 10−7    cm2/s: 5.9
 * Partial specific volume, V20: 0.733
 * Intrinsic viscosity, η: 0.0413
 * Frictional ratio, f/f0: 1.30
 * Refractive index increment (578 nm) × 10−3:    1.90
 * Optical absorbance, A279 nm1 g/L:    0.667
 * ε280 = 43.824 mM−1 cm−1
 * Mean residue rotation, [m']233: 8443
 * Mean residue ellipticity: 21.1 [θ]209 nm;    20.1 [θ]222 nm
 * Estimated a-helix, %: 54
 * Estimated b-form, %: 18

Applications[edit]
'''BSA has numerous biochemical applications including ELISAs (Enzyme-Linked Immunosorbent Assay), immunoblots, and immunohistochemistry. Because BSA is a small, stable, moderately non-reactive protein, it is often used as a blocker in immunohistochemistry. 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. This binding of BSA to nonspecific binding sites increases the chance that the antibodies will bind only to the antigens of interest. The BSA blocker improves sensitivity by decreasing background noise as the sites are covered with the moderately non-reactive protein. During this process, minimization of nonspecific binding of antibodies is essential in order to acquire the highest signal to noise ratio. BSA is also used as a nutrient in cell and microbial culture. 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. 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 (see Bradford protein assay). BSA is used because of its ability to increase signal in assays, 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. Another use for BSA is that it can be used to temporarily isolate substances that are blocking the activity of the enzyme that is needed, thus impeding polymerase chain reaction (PCR). BSA has been widely used as a template to synthesize nanostructures.'''

BSA is also the main constituent of fetal bovine serum, a common cell culture medium.

'''BSA is also used in vaccines (MMR, MMRV, Varicella, and Zoster). BSA is also used as a culture medium in artificial insemination.'''

'''A study covering the interactions of BSA and biomedical alloys has been used to provide more safe and success in implantation of biomedical devices. The interactions of albumin and biomedical alloys is dependent on solution properties (pH, temperature, and ionic strength), material properties (chemical composition, wettability, change, roughness, and surface energy), and protein properties (type and concentration). There are four mechanisms in which BSA interacts with biomedical alloys specifically 316L steel, CoCrMo, and Titanium. The four interactions are as follows; precipitation, protein-metal binding, adsorption, and reduction. BSA adsorption occurs in the binding of BSA to the metal surface which causes the formation of layered film. Reduction can be induced by electro chemicals and results in the reformation in disulfide bonds. Albumin precipitation involves the organometallic complexes from solution. [2]'''

'''Serum albumins due to its structure and sequence 26 have been identified as allergens by Algerome. The allergy to cow's milk is one of the most common but only about 15% continues past the age of five and usually associated with allergy to BSA. The individuals with an allergy to BSA have an increased risk of rhino conjunctivitis and asthma. infrequently BSA causes anaphylactic shock. Thorough cooking of food as been hypothesized to help the allergic reactions to BSA. Since there is high similarity between HSA and BSA the allergy to BSA is unusual.'''