Thermal denaturation of proteins is critical to cell injury, food science and other biomaterial processing. For example protein denaturation correlates strongly with cell death by heating, and is increasingly of interest in focal thermal therapies of cancer and other diseases at temperatures which often exceed 50 °C. The Arrhenius model is a simple yet widely used model for both protein denaturation and cell injury. To establish the utility of the Arrhenius model for protein denaturation at 50 °C and above its sensitivities to the kinetic parameters (activation energy Ea and frequency factor A) were carefully examined. We propose a simplified correlated parameter fit to the Arrhenius model by treating Ea, as an independent fitting parameter and allowing A to follow dependently. The utility of the correlated parameter fit is demonstrated on thermal denaturation of proteins and cells from the literature as a validation, and new experimental measurements in our lab using FTIR spectroscopy to demonstrate broad applicability of this method. Finally, we demonstrate that the end-temperature within which the denaturation is measured is important and changes the kinetics. Specifically, higher Ea and A parameters were found at low end-temperature (50 °C) and reduce as end-temperatures increase to 70 °C. This trend is consistent with Arrhenius parameters for cell injury in the literature that are significantly higher for clonogenics (45–50 °C) vs. membrane dye assays (60–70 °C). Future opportunities to monitor cell injury by spectroscopic measurement of protein denaturation are discussed.
Bibliographical noteFunding Information:
This project was financially supported by the National Institute of Health (NIH) R01-CA07528. W.F.W. performed work in Minnesota and Hannover for this project and was supported in part by funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) for the Cluster of Excellence REBIRTH (From Regenerative Biology to Reconstructive Therapy). Z.Q was supported by an Interdisciplinary Doctoral Fellowship and Doctoral Dissertation Fellowship. J.C.B. was supported by McKnight Professorship and Carl and Janet Kuhr-meyer Chair in Mechanical Engineering. J.A.P. received partial support for his investigations from the T.L.L. Temple and O-Donnell Foundations, and from Transonic/Scisense Inc. We thank Dr. Neil Wright for his insightful comments.
© 2014, Biomedical Engineering Society.
- Differential scanning calorimetry
- Enthalpy–entropy compensation
- Protein denaturation
- Thermal therapy