A4503 Sigma-Aldrich

Bovine Serum Albumin

cold ethanol fraction, pH 5.2, ≥96%

Synonym: Albumin bovine serum, BSA, Bovine albumin



Related Categories Albumin, Albumins, Biochemicals and Reagents, Bovine Serum Albumins, Buffers and Reagents,
biological source   bovine
assay   ≥96%
form   lyophilized powder
mol wt   ~66 kDa
purified by   cold ethanol fractionation
origin   USA origin
application(s)   ELISA: suitable
  blood typing: suitable
  microbiological culture: suitable
loss   ≤5%
pH   5.2
solubility   water: soluble (40 mg/ml)
storage temp.   2-8°C
Gene Information   bovine ... ALB(280717)


General description

Bovine serum albumin is a model protein in various studies and is made up of 583 amino acids. It is a water-soluble protein with a molecular weight of 66.4kDa. 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.


• Bovine Serum Albumin has been used in solution prepared for the isolation of heart mitochondria.
• It has been used in the cytotoxicity assay buffer.
• It has been used for the induction of protein overload nephropathy in rats.


1, 5 kg in poly drum

10, 50, 100, 500 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

Often referred to as Cohn fraction V; this product is prepared by a modified method of the Cohn cold ethanol fractionation method.

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.

Safety & Documentation

Safety Information

Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable

Frequently Asked Questions

Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
Is Product No. A4503, Albumin from bovine serum,tested and found to be protease-free?
No. If you need such a grade, we would recommend Product No. A3059.
Is Product No. A4503, Albumin from bovine serum,tested and found to be endotoxin-free?
No. If you need such a grade, we would recommend Product No. A8806.
Is Product No. A4503, Albumin from bovine serum,of US origin?
It is typically from animals born and raised in the US. You may confirm this information by downloading the Certificate of Origin (CofO) for any lot of A4503 from our website. From the product detail page, simply type in the lot number in the box below the words Certificate of Origin, and click GO"."
Is Product No. A4053, Albumin from bovine serum,sterile? If not, how would recommend sterilizing it?
This product is not necessarily sterile. Solutions of albumin cannot be autoclaved, so in order to sterilize it we would recommend that it be dissolved in the appropriate medium (water, saline or buffered saline), followed by sterile filtration through a low protein-binding membrane.
Do you offer a kit for conjugating ligands to bovine serum albumin (Product A4503)?
Yes. It is our Product No. MBK1.
How do I find price and availability?
There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote. USA customers: 1-800-325-3010 or view local office numbers.
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
My question is not addressed here, how can I contact Technical Service for assistance?
Ask a Scientist here.
My question is not addressed here, how can I contact Technical Service for assistance?
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Protocols & Articles


Guidelines for Bioassays on MultiScreen Filter Plates: Protein Binding and Cell Loading

The MultiScreen Assay System is well suited for a variety of separation techniques, including cell separations and solid phase bioassays. The MultiScreen system makes it possible to carry out an enti...
Keywords: Buffers, Cell culture, Cell proliferation, Chromatography, Filtration, Individual protein Immunoprecipitation, Precipitation, Protein assay, Reductions, Sample preparations, Scintillation, Separation


Enzymatic Assay of Hyaluronidase (

This procedure is a turbidimetric determination (% Transmittance at 600 nm, Light path = 1 cm) of Hyaluronidase activity. It is based on the following reaction:
Keywords: Extinction coefficient

Enzymatic Assay of L-Lactic Dehydrogenase (EC

To standardize a procedure for the assay of L-Lactic Dehydrogenase for all sources from heart muscle.
Keywords: Extinction coefficient

Enzymatic Assay of Myokinase (EC

Replaces OP SP-ADP01. New document assigned to conform to current document numbering system. Refer to CR SOP-DEK-ENZ47.
Keywords: Extinction coefficient, Molecular biology

Enzymatic Assay of Nuclease S1, Product No. N5661

3.2 Unit Definition – One unit will cause 1.0 microgram of single-stranded nucleic acid to become perchloric acid soluble per minute at pH 4.6 at 37ºC.

Enzymatic Assay of Peroxidase (EC 2,2'-Azino-bis(3-Ethylbenzthiazoline-6-Sulfonic Acid) as a Substrate

Replaces SPABTS02. Procedure updated to conform to current QUMAS formatting guidelines. Refer to CR SOP-DEK-ENZ42.
Keywords: Extinction coefficient

Enzymatic Assay of β-Glucuronidase (EC from E. coli

The scope of this procedure is all products from E. coli that have a specification for β-Glucuronidase activity.
Keywords: Enzymology

Enzymatic assay of lipase type XIII from Pseudomonas sp. and Pseudomonas cepacia using a coupled enzyme system of glycerol kinase and glycerophosphate oxidase (EC

To standardize a procedure for the enzymatic assay of Lipase Type XIII from Pseudomonas sp., Product No. L9518 , and Pseudomonas cepacia, using a coupled enzyme system of glycerol kinase and glycerop...
Keywords: Centrifugation, Extinction coefficient, High performance liquid chromatography, Size-exclusion chromatography

Related Content

Albumin in Cell Culture

Importance and uses of albumin in serum-free eukaryotic, including hybridoma and Chinese Hamster Ovary (CHO) cell cultures
Keywords: Cell culture, Culture media, Degradations, Hormones, Ligands, Oxidations, PAGE, Purification, Redox Reactions

Peer-Reviewed Papers


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