What is "bovine serum albumin"

Protein \Pro"te*in\, n. [Gr. prw^tos first: cf. prwtei^on the first place.] (Physiol. Chem.) any polymer of an amino acid joined by peptide (amide) bonds. Most natural proteins have alpha-amino acids as the monomeric constituents. All classical enzymes are composed of protein, and control most of the biochemical transformations carrie dout in living cells. They may be soluble, as casein, albumins, and other globular proteins, or insoluble (e. g. "structural proteins"), as collagen or keratin. "albumin", an older term for protein, is now used primarily to refer to certain specific soluble globular proteins found in eggs or blood serum, e.g. bovine serum albumin, the main soluble protein in teh serum of cattle, used as an enzymatically inert protein in biochemical research.

Note: In the 1913 dictionary, protein was defined as: ``A body now known as alkali albumin, but originally considered to be the basis of all albuminous substances, whence its name.''

Protein crystal. (Bot.) See Crystalloid, n., 2.

Bovine serum albumin (also known as 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.