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C2910 Sigma-Aldrich

Complement C3 from human serum

≥3000 C3H50 units/mg (using C3 deficient serum)



Related Categories Application Index, Biochemicals and Reagents, Cell Biology, Cell Signaling Enzymes, Cell Signaling and Neuroscience,
Quality Level   200
biological source   human
assay   ≥85% (SDS-GE)
form   solution
specific activity   ≥3000 C3H50 units/mg (using C3 deficient serum)
mol wt   185 kDa (disulfide-linked heterodimer)
application(s)   activity assay: suitable
shipped in   dry ice
storage temp.   −70°C
Gene Information   human ... C3(718)



Complement C3 is important in complement activation through the classical and alternative pathways. Complement C3 has been used in studies of bacterial defense against the complement system. Research on streptococcus infection has shown that Streptococcal pyrogenic exotoxin B (SPE B), a cysteine protease, can prevent phagocytic activity via cleavage of the C3 and impairing the pathways of the compliment system. C3 deficiency can result in recurrent infections and immune complex disorders. Recent research has shown that inherited C3 deficiency can occur either through homozygous mutations or through compound heterozygous mutations,

Biochem/physiol Actions

Complement C3 is the third and most abundant component of the complement pathway. It plays a central role in complement activation, being involved in both the classical and alternative pathways. C3 or its proteolytic fragments mediate many biological functions such as opsonization and anaphylatoxin activities. Pro-C3 is synthesized as a large single chain of 185 kDa and is processed to a disulfide-linked heterodimer consisting of an α-chain (115 kDa) and a β-chain (70 kDa) in the plasma. C3 is cleaved by the C3 convertases in either pathway (C4b2a, C3iBb, C3bBb) to C3b (176 kDa) comprised of the large C-terminal portion of the α-chain and the β-chain. C3b interacts with other complement components to initiate the amplification cascade. Studies of C3 function have been facilitated by experimentally induced C3 deficiency in animals by injection of cobra venom factor and more recently with gene ablation technology.


Functionally pure by a hemolytic assay using deficient sera.

Physical form

Supplied as a solution in PBS, pH 7.2.

Other Notes

View more information on the complement pathway at www.sigma-aldrich.com/enzymeexplorer

Safety & Documentation

Safety Information

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


Certificate of Analysis (COA)

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Certificate of Origin (COO)

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Frequently Asked Questions

How does the storage temperature relate to shipping conditions?
The storage conditions that a Sigma-Aldrich catalog and label recommend for products are deliberately conservative. For many products, long-term storage at low temperatures will increase the time during which they are expected to remain in specification and therefore are labeled accordingly. Where short-term storage, shipping time frame, or exposure to conditions other than those recommended for long-term storage will not affect product quality, Sigma-Aldrich will ship at ambient temperature. The products sensitive to short-term exposure to conditions other than their recommended long-term storage are shipped on wet or dry ice. Ambient temperature shipping helps to control shipping costs for our customers. At any time, our customers can request wet- or dry-ice shipment, but the special handling is at customer expense if our product history indicates that the product is stable for regular shipment. See Shipping and Storage for more information.
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.
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The lot specific COA document can be found by entering the lot number above under the "Documents" section.
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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.
What is the molecular weight of Product C2910, Complement C3 from human serum?
The molecular weight ofProduct C2910, Complement C3 from human serum, is approximately 185 kDa. It is composed of 2 nonidenticalpolypeptide chains. The A chain is approximately 110 kDa and the B chain is approximately 70 kDa.
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