Advertisement

Differences in Hydration Structure Around Hydrophobic and Hydrophilic Model Peptides Probed by THz Spectroscopy

  • Hanna Wirtz
  • Sarah Schäfer
  • Claudius Hoberg
  • Martina Havenith
Article
  • 310 Downloads

Abstract

We have recorded the THz spectra of the peptides NALA and NAGA as well as the amino acid leucine as model systems for hydrophobic and hydrophilic hydration. The spectra were recorded as a function of temperature and concentration and were analyzed in terms of a principal component analysis approach. NAGA shows positive absorptions with an increasing effective absorption coefficient for increasing concentrations. We conclude that NAGA due to its polar and hydrophilic structure does not have a significant influence on the surrounding water network, but is instead integrated into the water network forming a supramolecular complex. In contrast, for NALA, one hydrogen atom is substituted by a hydrophobic iso-butyl chain. We observe for NALA a decrease in absorption below 1.5 THz and a nonlinearity with a turning point around 0.75 M. Our measurements indicate that the first hydration shell of NALA is still intact at 0.75 M (corresponding to 65 water molecules per NALA). However, for larger concentrations the hydration shells can overlap, which explains the nonlinearity. For leucine, the changes in the spectrum occur at smaller concentrations. This might indicate that leucine exhibits a long-range effect on the solvating water network.

Keywords

Hydrophobic Hydration Hydrophilic Hydration Model Peptides Solvation science 

Notes

Acknowledgments

We thank J. Savolainen for helpful discussions when setting up the THz—time-domain laser system and G. Schwaab for his support when analysing the data.

Funding Information

This work is part of the Cluster of Excellence Ruhr Explores Solvation (RESOLV) (EXC 1069) funded by the Deutsche Forschungsgemeinschaft.

References

  1. 1.
    Acbas, G., Niessen, K. A., Snell, E. H. & Markelz, A. G. Optical measurements of long-range protein vibrations. Nat. Commun. 5, 1–7 (2014).CrossRefGoogle Scholar
  2. 2.
    Born, B., Weingärtner, H., Bründermann, E. & Havenith, M. Solvation dynamics of model peptides probed by terahertz spectroscopy. observation of the onset of collective network motions. J. Am. Chem. Soc. 131, 3752–3755 (2009).CrossRefGoogle Scholar
  3. 3.
    Born, B. & Havenith, M. Terahertz dance of proteins and sugars with water. in Journal of Infrared, Millimeter, and Terahertz Waves 30, 1245–1254 (2009).Google Scholar
  4. 4.
    Heugen, U. et al. Solute-induced retardation of water dynamics probed directly by terahertz spectroscopy. Proc. Natl. Acad. Sci. U. S. A. 103, 12301–6 (2006).CrossRefGoogle Scholar
  5. 5.
    Born, B., Kim, S. J., Ebbinghaus, S., Gruebele, M. & Havenith, M. The terahertz dance of water with the proteins: the effect of protein flexibility on the dynamical hydration shell of ubiquitin. Faraday Discuss. 141, 161–173 (2009).CrossRefGoogle Scholar
  6. 6.
    Xu, Y. & Havenith, M. Perspective: watching low-frequency vibrations of water in biomolecular recognition by THz spectroscopy. J. Chem. Phys. 143, 170901 (2015).CrossRefGoogle Scholar
  7. 7.
    Heyden, M. et al. Long-range influence of carbohydrates on the solvation dynamics of water-answers from terahertz absorption measurements and molecular modeling simulations. J. Am. Chem. Soc. 130, 5773–5779 (2008).CrossRefGoogle Scholar
  8. 8.
    Heyden, M. & Havenith, M. Combining THz spectroscopy and MD simulations to study protein-hydration coupling. Methods 52, 74–83 (2010).CrossRefGoogle Scholar
  9. 9.
    Fogarty, A. C. & Laage, D. Water dynamics in protein hydration shells: the molecular origin of the dynamical perturbation. J. Phys. Chem. B 118, 7715–7729 (2014).CrossRefGoogle Scholar
  10. 10.
    Laage, D., Elsaesser, T. & Hynes, J. T. Perspective: structure and ultrafast dynamics of biomolecular hydration shells. Struct. Dyn. 4, 44018 (2017).CrossRefGoogle Scholar
  11. 11.
    Nibali, V. C. & Havenith, M. New insights into the role of water in biological function: studying solvated biomolecules using terahertz absorption spectroscopy in conjunction with molecular dynamics simulations. J. Am. Chem. Soc. 136, 12800–12807 (2014).CrossRefGoogle Scholar
  12. 12.
    Heyden, M. & Tobias, D. J. Spatial dependence of protein-water collective hydrogen-bond dynamics. Phys. Rev. Lett. 111, 218101 (2013).CrossRefGoogle Scholar
  13. 13.
    Rezus, Y. L. A. & Bakker, H. J. Observation of immobilized water molecules around hydrophobic groups. Phys. Rev. Lett. 99, 148301 (2007).CrossRefGoogle Scholar
  14. 14.
    Funkner, S., Havenith, M. & Schwaab, G. Urea, a structure breaker? Answers from THz absorption spectroscopy. J. Phys. Chem. B 116, 13374–13380 (2012).CrossRefGoogle Scholar
  15. 15.
    Murarka, R. K. & Head-Gordon, T. Dielectric relaxation of aqueous solutions of hydrophilic versus amphiphilic peptides. J. Phys. Chem. B 112, 179–186 (2008).CrossRefGoogle Scholar
  16. 16.
    Head-Gordon, T., Sorenson, J. M., Pertsemlidis, A. & Glaeser, R. M. Differences in hydration structure near hydrophobic and hydrophilic amino acids. Biophys. J. 73, 2106–2115 (1997).CrossRefGoogle Scholar
  17. 17.
    Murarka, R. K. & Head-Gordon, T. Single particle and collective hydration dynamics for hydrophobic and hydrophilic peptides. J. Chem. Phys. 126, 215101 (2007).CrossRefGoogle Scholar
  18. 18.
    Niehues, G., Heyden, M., Schmidt, D. A. & Havenith, M. Exploring hydrophobicity by THz absorption spectroscopy of solvated amino acids. Faraday Discuss. 150, 193–207 (2011).CrossRefGoogle Scholar
  19. 19.
    Comez, L. et al. More is different: experimental results on the effect of biomolecules on the dynamics of hydration water. J. Phys. Chem. Lett. 4, 1188–1192 (2013).CrossRefGoogle Scholar
  20. 20.
    Sasisanker, P. & Weingärtner, H. Hydration dynamics of water near an amphiphilic model peptide at low hydration levels: a dielectric relaxation study. ChemPhysChem 9, 2802–2808 (2008).CrossRefGoogle Scholar
  21. 21.
    Head-Gordon, T. Is water structure around hydrophobic groups clathrate-like? Proc. Natl. Acad. Sci. U. S. A. 92, 8308–8312 (1995).CrossRefGoogle Scholar
  22. 22.
    Russo, D., Murarka, R. K., Copley, J. R. D. & Head-Gordon, T. Molecular view of water dynamics near model peptides. J. Phys. Chem. B 109, 12966–75 (2005).CrossRefGoogle Scholar
  23. 23.
    Pertsemlidis, A., Saxena, A. M., Soper, A. K., Head-Gordon, T. & Glaeser, R. M. Direct evidence for modified solvent structure within the hydration shell of a hydrophobic amino acid. Proc. Natl. Acad. Sci. U. S. A. 93, 10769–10774 (1996).CrossRefGoogle Scholar
  24. 24.
    Gallagher, K. R. & Sharp, K. A. A new angle on heat capacity changes in hydrophobic solvation. J. Am. Chem. Soc. 125, 9853–9860 (2003).CrossRefGoogle Scholar
  25. 25.
    Laage, D. & Hynes, J. T. On the molecular mechanism of water reorientation. J. Phys. Chem. B 112, 14230–14242 (2008).CrossRefGoogle Scholar
  26. 26.
    Laage, D. & Hynes, JT. A molecular jump mechanism of water reorientation. Science (80). 311, 832–835 (2006).CrossRefGoogle Scholar
  27. 27.
    Sharp, K. A., Madan, B., Manas, E. & Vanderkooi, J. M. Water structure changes induced by hydrophobic and polar solutes revealed by simulations and infrared spectroscopy. J. Chem. Phys. 114, 1791–1796 (2001).CrossRefGoogle Scholar
  28. 28.
    Sharp, K. A. Water: structure and properties. in eLS (2001).Google Scholar
  29. 29.
    Sharma, V., Böhm, F., Schwaab, G. & Havenith, M. The low frequency motions of solvated Mn(II) and Ni(II) ions and their halide complexes. Phys. Chem. Chem. Phys. 16, 25101–25110 (2014).CrossRefGoogle Scholar
  30. 30.
    Wold, S., Esbensen, K. & Geladi, P. Principal component analysis. Chemom. Intell. Lab. Syst. 2, 37–52 (1987).CrossRefGoogle Scholar
  31. 31.
    Abdi, H. & Williams, L. J. Principal component analysis. WIREs Comp Stat 2, 433–459 (2010).CrossRefGoogle Scholar
  32. 32.
    Kessler, W. Multivariate Datenanalyse. (2007).Google Scholar
  33. 33.
    Decka, D., Schwaab, G. & Havenith, M. A THz/FTIR fingerprint of the solvated proton: evidence for Eigen structure and Zundel dynamics. Phys. Chem. Chem. Phys. 17, 11898–11907 (2015).CrossRefGoogle Scholar
  34. 34.
    Böhm, F., Schwaab, G. & Havenith, M. Mapping hydration water around alcohol chains by THz calorimetry. Angew. Chemie - Int. Ed. 56, 9981–9985 (2017).CrossRefGoogle Scholar
  35. 35.
    Sun, J. et al. Understanding THz spectra of aqueous solutions: glycine in light and heavy water. J. Am. Chem. Soc. 136, 5031–5038 (2014).CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Hanna Wirtz
    • 1
  • Sarah Schäfer
    • 1
  • Claudius Hoberg
    • 1
  • Martina Havenith
    • 1
  1. 1.Lehrstuhl für Physikalische Chemie IIRuhr Universität BochumBochumGermany

Personalised recommendations