MicroCal PEAQ-DSC – The Gold Standard for protein stability characterization

DSC is often referred to as the gold
standard technique for measuring the thermal stability of biological macromolecules. Most commonly, it is used for measuring protein stability in the biotherapeutic industry Most biologics are proteins or protein derivatives, such as, antibodies or antibody drug conjugates or ADC’s DSC’s ability to measure the thermal stability of all protein and protein derivatives is because the instrument can detect the small heats associated with the making and breaking of hydrogen bonds. These bonds are broken when the biologic is heated and it unfolds. A process which absorbs heat and is detected by the calorimeter. Most other techniques used to measure protein stability rely on monitoring the change in the environment of a particular amino acid, often a tryptophan. There are a number of problems with this approach. Firstly, not all proteins have tryptophan and the unfolding will not be observed, it will be invisible. Secondly, even if they do have the tryptophan, those techniques will only detect changes in the local environment of those amino acids. This may not be a good representation of the unfolding of the protein as a whole. This is particularly important for multi domain proteins. One or more of the domains may not have the tryptophan and therefore the unfolding of a particular
domain may go completely undetected. If this domain is important for the
stability of the biologic, then all the data used to assess the developability of that molecule will be misleading. Of course, there are examples where
spectroscopic techniques do detect unfolding of sub-domains. However, it is not easy to predict or know if the data is telling the whole story or not This unknown makes for very risky decision making. This is why many laboratories run MicroCal DSC measurements to validate their spectroscopic analyses. In addition to this, the new MicroCal PEAQ-DSC has new smart algorithms for picking up even subtle features
in DSC unfolding curves to facilitate the identification of sub-domain unfolding. There are a number of other advantages
of DSC over spectroscopic techniques. Firstly, MicroCal DSC can be used to
study biologics in a broad range of buffers and formulations which can be a problem for many other techniques. Secondly, DSC is designed to go to 130
degrees Celsius. Many spectroscopic techniques cannot be used above about 90 degrees Celsius which means that any highly stable proteins with TM’s, above about 75 degrees Celsius, cannot be studied. Thirdly, spectroscopic techniques
are prone to artifacts from turbid solutions, inner filtering, quenching and light scattering which plague fluorescence measurements and are often dependent on sample concentration. These phenomena can also lead to poor
reproducibility. It is the high reproducibility of DSC that has led to its use in batch to batch studies. DSC data has been used to support a number of successful biosimilar registration applications. In addition to these advantages the MicroCal DSC has low sample volume requirements and high compatibility with biological buffers. It can be run at fast scan rates reducing
experimental time and it has features that support working in a regulated environment including MAC software to support 21 CFR part 11 compliance.

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