Protein G / Agarose

Agarose for IgG purification

Protein G is an immunoglobulin-binding protein expressed in group C and G Streptococcal bacteria. It is a 65-kDa (G148 protein G) and a 58 kDa (C40 protein G) cell surface protein that has found application in purifying antibodies through its binding to the Fc region [1]. Protein G binds to most mammalian IgGs through the Fc region, but some binding also occurs through the Fab region.

Native protein G also binds albumin; however, because serum albumin is a major contaminant of antibody sources, the albumin binding site has been removed from recombinant forms of Protein G [2].

Protein G / Agarose from InvivoGen uses the recombinant form of protein G lacking the albumin-binding region.

Binding capacity of InvivoGen's Protein G:

• 20 mg of human IgG per ml of gel
• 15 mg of rabbit IgG per ml of gel
• 6 mg of mouse IgG per ml of gel

References:

1. Sjobring U. et al., 1991. Streptococcal Protein G. Gene structure and protein binding properties. J Biol Chem. 140:1194-1197.
2. Goward CR. et al., 1990. Expression and purification of truncated recombinant streptococccal Protein G. Biochem J. 267:171-177.