Possible Interaction of Terahertz Signals in Neurons with Tryptophan Multimers

Aromatic amino acids (AAAs) as a major constituent of microtubules in cells play an important role in multiple neural signaling processes. The microtubule has been shown to possibly transmit biophotons of cell mitochondria through its ordered structure. Recent studies show that terahertz waves presumably take part in transmission, modulation and enhancement of neural signals, the processes of which are shown inseparable to the amino acid multimers. Here we calculated the infrared spectra of tryptophan, an AAA which is prevalent in microtubule and building its scaffold. By calculating the vibrational modes of both the monomer and dimer of the tryptophan, we discovered two new and high-intensity peaks in the THz range interpreting the inter-molecular vibration, indicating energy convergence towards intermolecular interaction. The rest of the peaks presents a phase shift similar to the exciplex structure. Therefore, we propose that the multimer structure of tryptophan in tubulins may promote terahertz interaction in microtubules. This work presents a possibility of terahertz signal in neurons interacting with microtubules, demonstrating how terahertz electromagnetic signals may participate in the complex process of neural signal transmission.