05479 Sigma

Bovine Serum Albumin

fraction V, essentially protease free, ≥92% (GE)

Synonym: Albumin bovine serum, BSA, Bovine albumin



assay   ≥92% (GE)
form   lyophilized powder
quality   essentially protease free
mol wt   Mr ~67000
  mol wt ~66 kDa
purified by   heat shock fractionation
loss   ≤5% loss on drying
solubility   H2O: soluble40 mg/mL at 20 °C, clear, colorless to slightly yellow
  H2O: slightly soluble
foreign activity   protease ≤0.005 U/mg
storage temp.   2-8°C


Other Notes

Sales restrictions may apply

Preparation Note

Initial fractionation by heat shock.

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.


Albumin from bovine serum has been used for blocking the non-specific protein binding surface areas. It has also been used as a standard for evaluating the concentration of protein by using Bradford method.

Biochem/physiol Actions

Bovine serum albumin also referred to as BSA or Fraction V is a protein isolated from cows. BSA can block vacant binding sites in enzyme-linked immunosorbent assay (ELISA) in both poly-l-lysine (PLL)-treated as well as non-treated microwells. It can also triggers the insulin dependent diabetes mellitus.

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

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Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 


Certificate of Analysis

Protocols & Articles
Peer-Reviewed Papers


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