Study of the THz response of protein solutions at different stages of glycation
- Dr. Olga CHERKASOVA
- Dr. Olga CHERKASOVA (Institute of Laser Physics of SB RAS)
Protein glycation is accelerated under hyperglycemic conditions resulting in loss of the structure and biological functions of proteins. This process plays a significant role in diabetic complications in organism tissues. THz spectroscopy is unique tool that can be used for analysis of biological tissues and solutions because changes in relative proportions of free and bound water and in relaxation times for either of these states can all be observed in THz range. A distinctive feature of this method is the possibility of measuring directly the refractive index, absorption coefficient, and hence complex permittivity spectrum of the sample in a single scan and in a broad frequency range. The THz time-domain spectroscopy has been used for measuring of bovine serum albumin (BSA) and monosaccharides solutions and studying of glycation dynamics for 0-96 h incubation BSA with sugars. To detect small-scale changes in solutions and to increase the significance of observations, we have performed measurements using both transmission and attenuated total internal reflection (ATR). By combining the results obtained in both configurations, the reliable range of the spectrum can be considerably broadened (0.05-2.5 THz). The THz time-domain spectrometer used in the study was described previously . The Fourier transform of the measured pulse time profile provides the complex spectrum comprising information on the refractive and absorption indices of the medium where the pulse has been reflected or transmitted. To recalculate the transmission spectrum into the absorption and refraction spectra, we used the Fresnel formulas and the methods described in . We analyzed the reasons for the THz transmission changes of BSA and monosaccharides solution during incubation. The differences were analyzed by comparing experimental spectra to the model dielectric function of water. THz absorption coefficient of glycated albumin solution increases during first several days of incubation. Fructose demonstrated stronger and/or faster influence on THz absorption of BSA than glucose. We consider that glycation of BSA results in a change the parameters of slow Debye relaxation. These results show that THz spectroscopy is a useful tool for study of protein glycation in time.
 Nazarov, M. M., Shkurinov, A. P., Kuleshov, E. A., Tuchin, V. V., “Terahertz time-domain spectroscopy of biological tissues”, Quantum Electron. 38, 647-654 (2008).  Cherkasova, O.P., Nazarov, M. M., Angeluts, A.A., Shkurinov, A.P., “The Investigation of blood plasma in the terahertz frequency range”, Optics and Spectroscopy 120(1), 50-57(2016).
corresponding author: Cherkasova Olga Pavlovna, 630090, Novosibirsk, Prospect ak. Lavrent'ev, 13/3; E-mail: email@example.com Tel: (383) 330-99-22, 8-965-823-11-92