Immunoglobulin binding

Figure 24.2 Antigens may be detected in cells or tissue sections through the use of protein A-coated gold particles. The binding of a specific primary antibody to its target antigen can be localized by the immunoglobulin binding capability of protein A, which occurs in the Fc region of the antibody.

Staphylococcal protein A (SPA), with its immunoglobulin binding ability, has been used as an affinity tail for the purification of a human insulin growth factor-1 (lGF-1) fusion. The insertion of an acid-labile Asp-Pro cleavage site at the fusion point allowed the separation of the protein A moiety from lGF-1 (Nilsson et al., 1985). 

Ried, M.U., A. Girod, K. Leike, H. Buning, and M. Hallek, Adeno-associated virus capsids displaying immunoglobulin-binding domains permit antibody-mediated vector retargeting to specific cell surface receptors. J Virol, 2002. 76(9) 4559-66. 

The proteins at the heart of the humoral immune response are soluble proteins called antibodies or immunoglobulins, often abbreviated Ig. Immunoglobulins bind bacteria, viruses, or large molecules identified as foreign and target them for destruction. Making up 20% of blood protein, the immunoglobulins are produced by B lymphocytes, or B cells, so named because they complete their development in the feone marrow. 

Fig. 1 Structure of the thiophilic ligand created by the reaction of 2-mercaptoethanol with divinyl sulfone-activated agarose. Immunoglobulins bind to the adjacent sulfone and thioether groups.

Raghavan, M., Gastinel, L. N. and Bjorkman, P. J. (1993) The class I major histocompatibility complex related Fc receptor shows pH-dependent stability differences correlating with immunoglobulin binding and release. Biochemistry 32, 8654-8660. 

Elsayed, S. and Apold, J. 1983. Immunochemical analysis of cod fish allergen M Location of the immunoglobulin binding sites as demonstrated by the native and synthetic peptides. Allergy 38 449 159. 

Befus, A. D. (1977). Hymenolepis diminuta and H. microstoma mouse immunoglobulins binding to the tegumental surface. Experimental Parasitology, 41 242-51. 

Djojonegoro BM, Benedik MJ, Willson RC, Bacteriophage surface display of an immunoglobulin-binding domain of Staphylococcus aureus protein A, BioTechnology, 12 169-172, 1994. 

SpA-derived proteins containing different number and composition of domains have been produced by recombinant methods. The binding properties of intact SpA and some SpA-derived protein fragments to IgG, IgA, IgM, and F(ab )2 have been analyzed. The results suggest that the binding is affected both by the number of immunoglobulin binding domains and by the composition of the domains. 

---