Correlation between hydrogen/deuterium exchange and Amide I band intensity in hemoglobin aqueous solution under static or 50 Hz magnetic field

Samples of hemoglobin in deuterium oxide solution (D2O) and in bidistilled H2O water solution, both at the concentration of 100 mg/ml, were exposed to a static magnetic field at 100 mT; analogous samples were exposed to 50 Hz magnetic field at 1 mT. Fourier Transform Infrared (FTIR) Spectroscopy was used to analyze separately the response of the secondary structure of this protein (diluted in both aqueous solutions) to separated exposure to both magnetic fields. The most relevant result which was observed after exposures was the significant increasing in intensity of the Amide I band, which was already explained in previous studies assuming that proteins α-helix aligned along the direction of the applied magnetic field due to its large dipole moment. In particular, in this study it was shown that hydrogen/deuterium exchange induced a reduction of the increasing of Amide I vibration band. This result can be explained assuming that Amide hydrogens of hemoglobin exchange with solvent deuterium atoms, causing an increase in mass of the protein and a correlated increasing in inertia of the α-helix, reducing significantly the torque effect of the applied magnetic field.