A4503 Sigma

Bovine Serum Albumin

cold ethanol fraction, pH 5.2, ≥96%

Synonym: Albumin bovine serum, BSA, Bovine albumin



Frequently Asked Questions

Frequently Asked Questions are available for this Product.


1, 5 kg in poly drum

10, 50, 100, 500 g in poly bottle

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.


• 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.

Biochem/physiol Actions

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

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.

Price and Availability

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Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 

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. These documents are located on the product detail page under Useful Links & Tools. Click on the following link to search for a Certificate of Analysis. Please click the following link to see the details on our Product Dating Information.
How do I get lot-specific information or a Certificate of Analysis?
A Certificate of Analysis is available by lot number and can be obtained through our Advanced Search Option:
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. Here is a link to the technical bulletin for that kit:
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, or search here. 
My question is not addressed here, how can I contact Technical Service for assistance?
Use the option to the right to "Ask a Question" by email of a Technical Service Scientist.
I need help selecting an Albumin from bovine serum (BSA) product, is there a guide to help me choose the best product?
Yes,  a selection guide to our BSA products can be found at the link below:
Show more questions
Protocols & Articles


Enzymatic Assay of Hyaluronidase (

The turbidimetric determination (% Transmittance at 600 nm, Light path = 1 cm) 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 Lipase Type XIII from Pseudomonas Species 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 Species, Sigma Product Number L9518 , and Pseudomonas Cepacia, Sigma Product Number L9156, using a coupled enzy...
Keywords: Centrifugation, Extinction coefficient, High performance liquid chromatography

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

To standardize a procedure for the enzymatic assay of Nuclease S1, Sigma Product Number N5661 at Sigma-Aldrich St. Louis.

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

Related Content

Albumin in Cell Culture

Importance and uses of albumin in serum-free eucaryotic, 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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