Probing ultraviolet-induced dissociation of hydrogen bond networks in tyrosine by terahertz spectroscopy.

Tyrosine (Tyr) has gained significant attention as one of the most sensitive amino acids. Its oxidation is accompanied by changes in hydrogen bonds, so the oxidation process of Tyr is monitored and the dissociation sequence of different hydrogen bond network is elucidated based on the sensitivity of terahertz (THz) waves to intermolecular interactions. We find that the peak height of Tyr at 0.97 THz and 2.08 THz decreases with time, but the change behavior of the two is different. Combined with density functional theory (DFT), this phenomenon is attributed to the difference of factors that dominate THz vibration. The weakening of the peak height of Tyr at 0.97 THz is due to the ordered dissociation of hydrogen bonds with different intensities, while the peak at 2.08 THz mainly involves the lattice itself. This means that the peak at 0.97 THz is a more accurate parameter for characterizing the oxidation process. Our study reveals the hydrogen bond changes of Tyr when its structure is destroyed, and provides a spectral technique for monitoring and preventing harmful oxidation reactions using hydrogen bond network evolution.