The characterization of protein-based biologics requires many forms of analysis, given the complex nature of the drug substance and the limited ability of any one assay to provide comprehensive information on the myriad of protein structural attributes. Secondary structure, in the form of alpha helices, beta sheets, and other conformations, is a critical parameter in the stability, antigenicity, and functionality of a protein therapeutic, and therefore, must be assessed prior to its market approval.
One important tool used in structural characterization is the Fourier-Transform Infrared (FT-IR) spectrometer. FT-IR spectroscopy allows for the monitoring of vibrational modes of the amide bonds within a protein while in its native state and formulation matrix. While a protein will display many infrared-absorbing bands, amide bands I and II are quite sensitive and representative of the protein conformational states and are used to discern the relative amounts of different types of secondary structure. FT-IR is especially sensitive to types of beta sheet structure, which are abundant in antibodies. Together with circular dichroism, FT-IR is part of a comprehensive platform in the characterization of a biologic's secondary structure profile.
The newly acquired state-of-the-art Nicolet™ iS™ 50 FT-IR Spectrometer expands Charles River’s analytical capabilities to provide a more comprehensive and complete package towards protein higher order structural characterization. Conducting rapid and sensitive assays with a high degree of throughput, the spectrometer is designed to be flexible and can be upgraded from a simple FT-IR bench to a fully-automated multi-spectral range system that can acquire spectra from far-infrared to visible. Options include novel attenuated total reflection (ATR), Raman, and near-infrared (NIR) spectroscopy modules that can be enabled without manually changing system components. This new platform allows our biophysical division to expand services in support of client needs with higher order structural analysis in relation to overall biopharmaceutical characterization, comparability studies, and biosimilarity assessment.