Label-free protein interaction analysis is used extensively throughout academic research and in the pharmaceutical and biotechnology industries, playing a vital role in proteomic studies, small molecule drug discovery, biopharmaceutical development and clinical immunogenicity studies as well as manufacturing and QC.
Comprehensive characterization of how proteins interact with other molecules must include high quality information on parameters such as binding specificity, affinity (the strength of the interaction) and kinetics (the rates at which the interactants bind and dissociate). Interaction analysis systems from GE Healthcare (formerly Biacore AB) deliver such data by monitoring binding events in real-time, without the use of labels.
While proteins are the most commonly studied molecules, almost any class of interactant can be immobilized or used as the sample in solution, from LMW compounds of a few hundred Daltons, through to large macromolecules or even whole cells.
All Biacore systems are characterized by a similar label-free detection mode; the phenomenon of surface plasmon resonance (SPR) to detect mass concentration changes on a sensor surface. Using SPR, complex association and dissociation are detected in real time and data are presented graphically in an interaction profile known as a sensorgram.
The depth and scope of information provided by Biacore systems make it a highly attractive tool for the characterization of protein interactions. Besides the provision of high resolution kinetic data, it is possible with systems such as Biacore T100 to analyze interactions at physiological temperature, which improves the predictive value of data on biotherapeutics. The ability to analyze interactions without sample purification or concentration is a great advantage in the analysis of monoclonal antibodies in hybridoma supernatants, enabling the selection of promising candidates at an early stage in the development pipeline.
Protein interaction arrays have recently appeared, offering an information-rich, interaction-based technology rather than one with the emphasis purely on throughput. Biacore A100 delivers high information content while it is possible with Flexchip to simultaneously profile up to 400 protein interactions. Both these systems profile entire interactions, delivering information about the function of e.g. a group of antibodies or peptides. Protein interaction arrays may well prove to be the link between the vast repository of data that has emerged from proteomics initiatives and the world of clinical and biological research.
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