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    • Keywords

       

      Steady-state terahertz absorption spectroscopy; human serum albumin in aqueous solution; nonlinear increase of THz absorption with concentration; hydration layer; protein aggregation at high protein concentration.

    • Abstract

       

      Terahertz (THz) absorption behaviour of HSA protein in aqueous buffer solutions has been investigated in the 0.1–2 THz frequency range using a highly intense THz source based on coherent transition radiation (CTR) generated using a femtosecond electron accelerator of 42 MeV energy (for 0.3–2 THz) and aklystron (at 0.1 THz). Like in the cases of other proteins reported earlier, THz absorbance of the protein solutions follow nonlinear behaviour with increasing concentration of HSA protein monitored through the entire frequency range. THz absorbance of the solution initially increases to follow an apparently linearbehaviour up to the concentration of ~6 9 10-4 mol dm-3 but decreases gradually with further increase in HSA concentration. The linear behaviour in low concentration regime could be explained considering the increase in concentration of the monomer HSA molecules in solution with a well-defined hydration layer of thickness of about 22 A° around it. However, the study of dynamic light scattering measurements suggest the presence of increasing number of protein aggregates in solution with increasing concentration of protein. THz absorbance of each of these samples could be calculated to show that absorbance decreases with increasing number of aggregates in solution and also the relative concentrations of the monomer and aggregated particles existing in solutions could be estimated. This work, for the first time, explains the nonlinear change in THz absorbance of protein solutions with increasing protein concentration considering the protein aggregation effect at very high concentration.

    • Author Affiliations

       

      BISWAJIT MANNA1 AMITABHA NANDI1 MASAHITO TANAKA2 HIROYUKI TOYOKAWA2 RYUNOSUKE KURODA2 DIPAK K PALIT1 3

      1. Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
      2. Research Institute for Measurement and Analytical Instrumentation, National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
      3. UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Kalina Campus, Mumbai 400 098, India
    • Dates

       
  • Journal of Chemical Sciences | News

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