Destabilization of water molecules by terahertz electric fields affects sodium ion blockage in the Kv1.2 channel

Potassium channels are essential for various physiological functions, with their high selectivity being a critical foundation. The blockage of sodium ions in potassium channels is a crucial aspect of their selectivity, yet the underlying mechanism remains unclear. In this study, we investigated the mechanisms underlying the sodium ion blockage through molecular dynamics simulations. We found that when sodium ions bind to the B_{34} site, the water molecule at the entrance of the selectivity filter forms a strong association with the ion, preventing effective knock-on movement and resulting in a 93% loss of permeability. Given the vibrational frequencies of biomolecules within the terahertz range, terahertz waves are considered effective tools for biomolecular modulation. Consequently, we explored the influence of terahertz waves on the blockage of sodium ions. Our results show that a 15 THz electric field significantly disrupts the stable binding of the water molecule to the sodium ion at the B_{34} site, enhancing interactions between the ion in the cavity and those in the selectivity filter, thereby alleviating the blockage. This study reveals that the dynamic state of water molecules in biological systems is closely related to biomolecular functions and is influenced by external physical fields, such as terahertz electric fields. These findings provide new insights into potassium channels' selectivity mechanisms and broaden terahertz fields' potential applications in regulating channel functions.