The accuracy and precision of a new H/D exchange- and mass spectrometry-based technique for measuring the thermodynamic stability of proteins

Recently, we developed a new method for measuring the thermodynamic stability of proteins. The method, termed Stability of Unpurified Proteins from Rates of H/D Exchange (SUPREX), utilizes matrix-assisted laser desorption/ionization (MALDI) mass spectrometry and exploits the H/D exchange properties of proteins to determine folding free energies (i.e. ΔG°f values) for proteins. Here we report on the SUPREX analysis of seven new model proteins. The results of these analyses and the results of previously reported SUPREX analysis on seven additional proteins are used to assess the accuracy and precision of the SUPREX technique for measuring ΔG°f values. We find that the accuracy of the SUPREX technique for measuring the ΔG°f values of proteins is on the order of 20% and precision (relative standard deviation) of the technique is on the order 10%. These measures of accuracy and precision are comparable to those of conventional methods.

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