Terahertz Spectral Analysis of DNA Base Molecule Cytosine and Its Methylated Structure 5-Methylcytosine

摘要

Most DNA methylation occurs in the cytosine of nucleosides. In this study, the absorption coefficients of cytosine and5-methylcytosine were measured at 0.1-2.0 THz through terahertz time domain spectroscopy (THz-TDS) without beinglabeled. Our results showed that these important biomolecules had distinct spectral characteristics within this terahertzband. Moreover, structural optimization and lattice dynamics calculations were performed to determine the latticevibrational motions of both cytosine crystals and 5-methylcytosine crystals using the density functional theory (DFT)and the properly modeled intermolecular potentials. Typically, the lattice vibrational motion simulated the absorptionspectrum which indicated that the terahertz technique was able to detect the absorption spectral features of cytosine and5-methylcytosine. Hopefully, this study provided the molecular background to detect DNA methylation and lay certainfoundation for subsequent cancer detection.