FTIR as a Tool to Study Cold, Heat and Pressure Denaturation of Myoglobin

We studied the denaturation of horse heart metmyoglobin in the diamond anvil cell (DAC) with Fourier transform infrared spectroscopy (FTIR). It is observed that the conformational changes due to the cold and the pressure denaturation are similar, but not identical and that both processes do not lead to a complete loss of the secondary structure. Heat denaturation distinguishes itself from the former two processes by the formation of two new bands at 1615 and 1683 cm-1 which are characteristic for intermolecular β-sheet aggregation. This also explains why a gel can be observed at the end of the experiment. A gel, however, can also be observed in the case of a pressure denaturation. Some aspects of pressure- and heat-induced aggregation are discussed as well.