A5611 Sigma-Aldrich

Bovine Serum Albumin

Cohn Fraction V, lyophilized powder, ≥96% (agarose gel electrophoresis)

Synonym: Albumin bovine serum, BSA, Bovine albumin



Related Categories Albumin, Biochemicals and Reagents, Bovine Serum Albumins, Ethanol Fractionated, Proteins and Derivatives More...
biological source   bovine
assay   ≥96% (agarose gel electrophoresis)
form   lyophilized powder
mol wt   ~66 kDa
packaging   poly bottle of
pH   4.8-7.5
solubility   H2O: soluble 40 mg/mL, clear to slightly hazy, yellow
storage temp.   2-8°C


General description

Serum albumins are soluble constituents of the circulatory system. Bovine serum albumin (BSA) is homologous to human serum albumin (HSA). BSA consists of three homologous domains (I, II, III), that are separated into nine loops by disulfide bonds. Serum albumin acts as a depot protein.


Bovine Serum Albumin has been used:
• for in vitro high molecular weight (HMW)-species formation assay
• for immunohistochemistry
• in Escherichia coli quantitative polymerase chain reaction (qPCR) analysis


1, 5, 10 g in poly bottle

Biochem/physiol Actions

Certain conformational and primary-sequence epitopes of BSA are suspected allergens in human beef and milk allergies.

Preparation Note

Serum albumin may be referred to as Fraction V. This naming convention is taken from the original Cohn method of fractionating serum proteins using cold ethanol precipitation. Serum albumin was found in the fifth ethanol fraction using Cohn′s method. Since then, the term "Fraction V" has been used by some to describe serum albumin regardless of the method of preparation. Others have used this term to describe serum albumin purified by ethanol fractionation methods that have been highly modified since the original Cohn method was described. Sigma-Aldrich manufactures and distributes serum albumins purified from a variety of primary methods including the true Cohn fractionation method, modified ethanol fractionation methods, heat shock and chromatography. Additional purification steps may include crystallization or charcoal filtration.

This is a cold alcohol fractionated albumin that is produced by Sigma-Aldrich with a stricter adherence to the original Cohn method of fractionation than other commercially available bovine albumins.

Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 


Certificate of Analysis (COA)

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Certificate of Origin (COO)

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Protocols & Articles


Bovine Serum Albumin (BSA) Blocking Buffer Recipe

Bovine serum albumin (BSA) blocking buffer is ideal for saturating excess protein-binding sites on membranes and microplates for Western blotting and ELISA applications, respectively. Typically, 1-3%...
Keywords: Buffers, Detergents, Enzyme-linked immunosorbent assay, Western blot

Peer-Reviewed Papers


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