Abstract
Phosphorylation and dephosphorylation that are most remarkable posttranslational modifications are important to the activation and deactivation of protein in living system. In the first approach, we showed first that it is possible to distinguish a phosphate group in a peptide using Fourier Transform Infrared Spectrometer (FT-IR). In this study, we used Free Electron Laser (FEL) at the wavelength of 9.4 μm corresponding to the peak of infrared absorption spectra derived from a phosphate group in phosphorylated peptides to explore the irradiation effect of FEL on the phosphorylation of a peptide (experimental condition). This study demonstrated that the FEL irradiation had effects of some kind on the organization of infrared absorption of a phosphate group. The promotion of the phosphorylation by FEL irradiation is supposed via the excitation of both protein and phosphate reactant.
