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Bovine Serum Albumin

heat shock fraction, pH 7, ≥98%

Albumin bovine serum, BSA, Bovine albumin
CAS Number:
EC Number:
MDL number:

biological source


Quality Level




lyophilized powder

mol wt

~66 kDa

purified by

heat shock fractionation


USA origin


immunocytochemistry: suitable






water: soluble (40 mg/ml)

UniProt accession no.

storage temp.


Gene Information

bovine ... ALB(280717)

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General description

Bovine serum albumin is a protein whose key biological function is to regulate the colloidal osmotic pressure of blood. BSA is widely used in various studies and applications. Made up of 583 amino acids,[92][83] BSA is a water-soluble protein with a calculated molecular weight of 66,430 Da. Six α-helices form three homologous domains of BSA. Depending on pH, it undergoes reversible conformational isomerization. The native structure of the protein becomes reactive and flexible on heating.[94]


Bovine Serum Albumin is used for many applications, including the following applications:
  • BSA has been used in cell culture, e.g. as a supplement in media prepared for culturing of oligodendrocytes.
  • BSA has been used for the dilution of primary antibody solution in immunohistochemistry procedures.
  • [81]
  • BSA has been used as a standard in the Bradford method of protein quantification.
  • [82]
  • BSA has been used in blocking and permeabilization buffer for immunofluorescence studies.
  • [83]


    10, 50, 100, 500 g in poly bottle
    1 kg 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

    Prepared using heat shock fractionation
    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.

    Storage Class Code

    11 - Combustible Solids


    WGK 3

    Flash Point(F)

    Not applicable

    Flash Point(C)

    Not applicable

    Personal Protective Equipment

    dust mask type N95 (US), Eyeshields, Gloves

    Certificate of Analysis

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    Certificate of Origin

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    Product Information Sheet


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