Changzhou Smart-Lifesciences Biotechnology Co.,Ltd.

Natural Protein G is a cell wall protein isolated from G Streptococci that has two IgG binding regions, albumin, and cell surface binding sites. Recombinant protein G was expressed by Escherichia coli with a molecular weight of about 30 kDa(SDS-PAGE), which removed the binding site of albumin and cell surface and reduced the non-specific adsorption. Protein G has an optimal binding pH of 5.0, but is also good at pH 7.0-7.2. Compared with Protein A, Protein G has a stronger IgG binding force on most mammals, and it can also bind rats IgG2a, human IgG3 and mouse IgG1 that cannot bind well with Protein A. Protein G does not bind to human IgM, IgD and IgA. The difference in binding characteristics between Protein A and Protein G may be caused by the difference in the composition of IgG binding sites of the two proteins.