Comparison of surface plasmon resonance binding curves for characterization of protein interactions and analysis of screening data

Label-free technologies, such as surface plasmon resonance, are typically used for characterization of protein interactions and in screening for selection of antibodies or small molecules with preferred binding properties. In characterization, complete binding curves are normally fitted to defined interaction models to provide affinity and rate constants, whereas report points indicative of binding and stability of binding are often used for analysis of screening data. As an alternative to these procedures, here we describe how the analysis, in certain cases, can be simplified by comparison with upper and lower limit binding curves that represent expected or wanted binding profiles. The use of such profiles is applied to the analysis of kinetically complex IgG-Fc receptor interactions and for selection of antibody candidates. The comparison procedure described may be particularly useful in batch-to-batch comparisons and in comparability and biosimilar studies of biotherapeutic medicines. In screening, more informed selections may become possible as entire binding profiles and not a few report points are used in the analysis and as each new sample is directly compared with a predefined outcome.