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P6031

Sigma-Aldrich

Protein A from Staphylococcus aureus

Soluble, essentially salt-free, lyophilized powder, extracellular

Synonym(s):

Protein A resin

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About This Item

MDL number:
UNSPSC Code:
12352203
NACRES:
NA.46

biological source

Staphylococcus aureus

Quality Level

conjugate

unconjugated

form

essentially salt-free, lyophilized powder

capacity

7-14 mg/mg, solid binding capacity (human IgG)

solubility

H2O: soluble 1 mg/mL, clear, colorless

UniProt accession no.

storage temp.

2-8°C

Gene Information

Staphylococcus aureus subsp. aureus NCTC 8325 ... SAOUHSC_00069(3919448)

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General description

The bacterial strain is a derivative of a strain from Cohen, S., and Sweeney, H. M., J. Bact., 140, 1028 (1979).

Application

Protein A from Staphylococcus aureus has been used:
  • to coat nitrocellulose sheet with protein A for immunoassay of agalactosyl IgG.
  • as a blocking agent before the use of secondary antibody in immunohistochemistry.
  • as a binding agent to antibody during antibody immobilization.
Protein A may be conjugated with various reporter molecules including fluorescent dyes (FITC), enzyme markers (peroxidase, β-galactosidase, alkaline phosphatase), biotin, and colloidal gold without affecting the antibody binding site on the molecule. These conjugates are used to detect immunoglobulins in various immunochemical assays including western blotting, immunohistochemistry, and ELISA applications. In addition, protein A may be immobilized on a solid support such as agarose or acrylic beads for the purification of either polyclonal or monoclonal immunoglobulins. It is also routinely used for immunoprecipitation assays.

Biochem/physiol Actions

Protein A is a highly stable cell surface receptor produced by several strains of Staphylococcus aureus. It consists of a single polypeptide chain of molecular weight 42 kDa, containing four repetitive domains rich in aspartic and glutamic acids but devoid of cysteine. It contains little or no carbohydrate and only 4 tyrosine residues and no tryptophans. Protein A is capable of binding to the Fc portion of immunoglobulins, especially IgGs, from a large number of species. One protein A molecule has been shown to bind at least 2 molecules of IgG simultaneously. The IgG binding domain of Protein A consists of three anti-parallel α-helicies, the third of which is disrupted when the protein is complexed with the Fc region of the immunoglobulins. Protein A will bind the Fc portion of human IgG subclasses, IgM, IgA and IgE; and mouse IgG1 (weakly), IgG2a, and IgG2b. Protein A also binds IgGs from other species, including monkey, rabbit, pig, guinea pig, dog, and cat.
Protein A also participates in a number of different protective biological functions including anti-tumor, toxic, and carcinogenic activities. In addition to acting as an immunomodulator, it also has antifungal and antiparasitic properties.

Preparation Note

Purified from culture medium of a protein A-secreting S. aureus strain.

Disclaimer

Unless otherwise stated in our catalog or other company documentation accompanying the product(s), our products are intended for research use only and are not to be used for any other purpose, which includes but is not limited to, unauthorized commercial uses, in vitro diagnostic uses, ex vivo or in vivo therapeutic uses or any type of consumption or application to humans or animals.

Storage Class Code

11 - Combustible Solids

WGK

WGK 3

Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Certificates of Analysis (COA)

Search for Certificates of Analysis (COA) by entering the products Lot/Batch Number. Lot and Batch Numbers can be found on a product’s label following the words ‘Lot’ or ‘Batch’.

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The proportion of oligosaccharide chains on the Fc fragment of IgG which terminate with N-acetylglucosamine (GlcNAc) rather than galactose is increased in rheumatoid arthritis and tuberculosis, and in sera from patients with Crohn's disease, probably because of decreased activity of
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Antibody fragmentation with our pepsin digestion protocol for IgG antibody fragmentation and preparation of F(ab’).

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