Dynamic Detection of Thiol Oxidation/Reduction Status During the Conversion of Cysteine/Cystine

Abstract

• Dynamic detection of thiol oxidation/reduction status during the conversion of cysteine/cystine. • The thiol redox state is intuitively reflected by terahertz spectroscopy and Raman spectroscopy in varying degrees. The thiol redox state (TRS) plays a key role in evaluating essential biochemical processes, such as evaluating intracellular enzymatic activity. The TRS, characterized by the kinetic parameters of the thiol (–SH)/disulfide bond (–SS–) redox process, was measured by the Fourier-transform Raman spectroscopy (FT–Raman) and the terahertz time-domain spectroscopy (THz–TDS) in this study. A good correlation was observed between the disulfide concentration in samples and the intensities of the disulfide characteristic peaks in the FT–Raman and THz–TDS spectra. And the linear regression analysis correlation coefficients had values of 92.2% for FT–Raman-derived data and 95.4% for THz–TDS-derived data. The dynamic response of the cysteine/cystine experimental spectrum and characteristic peaks were analyzed by solid-state density functional theory. It can be found that both Raman and terahertz vibrational spectroscopy techniques can quantitatively analyze the ratio of cysteine/cystine. This provides a new method for the biological analysis of sulfur-containing amino acids and other related mixtures in basic science.