Abstract
Interaction between proteins and immunoglobins (IgGs) was studied using Dual Polarization Interferometry (DPI).Staphylococcal Protein A (SpA) and Streptococcal Protein G (SpG) were immobilized on a sensor surface previously derivatized using 3-isocyanatopropyltriethoxysilane (ICPTS) or N-γ-maleimidobutyryl-oxysulfosuccinimide ester (SulfoGMBS). Mass and thickness variation registered during the interaction were used to distinguish between IgG monomers and dimers. As a result of this study two different mechanisms for the monomeric IgG-SpA and dimeric IgG-SpG interactions were elucidated. Two elementary steps were observed in both cases, however SpA was able to bind two IgG monomers sequentially, whereas SpG bound only one IgG dimer and the resulting adduct experimented a further reorganization.
