I would like to detect human immunoglobulins which are not involved in imme reactions without using other immunoglobulins or protein A or G to avoid any background reaction.
Protein L could be the nearest possible alternative to rotein A and G
Per Invivogen prdoduct literature:
"Protein L is an immunoglobulin-binding protein expressed by the anaerobic species Peptostreptococcus magnus1 . Protein L binds specifically to the variable domain of Ig kappa light chain without interfering with the antigen-binding site2. It binds strongly to human kappa light chain subclasses I, III and IV, and also to most kappa light chains of other species such as rat and mouse. As it recognizes kappa light chains of other chains, protein L can bind to all classes of Ig, in contrast to Protein A and Protein G which interact with the Fc region and bind exclusively to IgG heavy chains. Protein L does not bind bovine immunoglobulins which are present in the fetal bovine serum (FBS) and thus provides a convenient way to purify kappa light chain-containing monoclonal antibodies from culture supernatant.
Protein L / Agarose from InvivoGen uses the recombinant form of protein L coupled to beads using a leak-resistant chemistry that provides a support with minimal nonspecific binding. Its binding capacity is 5-10 mg of human IgA/IgG per ml of gel.
1. Bjorck L. et al., 1998. Protein L. A novel bacterial cell wall protein with affinity for Ig L chains. J Immunol. 140:1194-1197.
2. Nilson BH. et al., 1993. Purification of antibodies using protein L-binding framework structures in the light chain variable domain. J Immunol Methods. 164:33-40."
First I want to thank you for your suggestions on how to determine Ka of MAb vs polysaccharides. With regard to your question on related proteins that bind human immunoglobulin, I think that Protein L is a good option