Novel approach to protein-protein interaction assessment

Past decades, the study of proteins and small molecules interaction has been at least lagging behind the study of other types of interactions such as protein-protein, protein-DNA and protein-RNA. The aim of this study is to evaluate the effect of low-molecular biologically active compounds, lactate and pyruvate, on protein-protein interactions and to provide quantitative assessment. Using AB0 blood groups system model and labeled monoclonal anti-A and anti-B antibodies we studied the effect of natural metabolites lactate and pyruvate on antigen-antibody interaction. Erythrocytes of A(II) and B(III) blood groups were incubated with lactate and pyruvate before the agglutination reaction. Then the agglutination reaction was performed. Visualization of agglutination complexes was carried out by means of confocal laser scanning microscopy with further processing of noise pixels. A series of in vitro experiments with further visualization and mathematical processing showed the co-directed but more pronounced effect of lactate on the antigen-antibody reaction as compared to pyruvate. In case of influence on antigen A the aggregation process intensification was noted, while this process was inhibited in case of influence on antigen B. The obtained results demonstrate possibility of using small molecules, in particular lactate and pyruvate, as molecular probes and prospects of erythrocytes with antigenic determinants of AB0 system expressed on their membranes for studying protein-protein interactions due to visualization clarity and possibility of quantitative assessment of this process. It is proved that lactate and pyruvate can act as regulators of protein-protein interactions on the example of antigen-antibody reaction.