Advertisement

Quantitative characterization of temperature-independent polymer–polymer interaction and temperature-dependent protein–protein and protein–polymer interactions in concentrated polymer solutions

  • Adedayo A FodekeEmail author
Original Article
  • 19 Downloads

Abstract

To study the effect of non-specific interactions arising from proteins being in a crowded environment on physiological processes, the self-interaction of concentrated Dextran T70 and Ficoll 70 and the interactions between a dilute protein and these polymeric macromolecules were quantified using non-ideal tracer sedimentation equilibrium. Sedimentation equilibria of each polymer were measured between 5 and 37 °C, and sedimentation equilibria of 2 mg cm−3 superoxide dismutase (SOD) in 0–0.1 g cm−3 of each polymer was also measured. Results were analyzed using a model-free thermodynamic virial expression of activity coefficients in terms of the concentration of polymer and a structural model using a statistical thermodynamics approximation. The equilibrium gradients of each of the polymers suggest repulsive interaction, which is independent of temperature. However, the net repulsive interaction between superoxide dismutase (SOD) species and the polymers is dependent on temperature. The ratio of the solvation energy of SOD in Dextran T70 to that in Ficoll 70, lnγSOD(Dex)/lnγSOD(Fic) at the same w/v concentration was about 1.8 at 37 °C, 1.6 at the intermediate temperature, and ranges from 1.2 to 1.6 at 5 °C over the entire concentration range. The enthalpy and entropy of interaction of SOD with dilute Dextran T70 are − 14 kJ mol−1 and − 5.6 J K−1 mol−1, respectively. For SOD in dilute Ficoll 70, the enthalpy and entropy are − 8.1 kJ mol−1 and 12.9 J K−1 mol−1, respectively. Thus, Dextran T70 contributes more to the attractive protein–polymer interaction and to self-association of protein than Ficoll 70 and reasons for this are discussed.

Keywords

Macromolecular crowding Protein–protein interactions Attractive forces Ficoll 70 Dextran T70 Superoxide dismutase 

Notes

Acknowledgements

The author thanks Dr. A. P Minton for making the facilities in his laboratory available for this work and for useful suggestions. The author is also grateful to Prof. K.O. Okojo for proofreading the manuscript.

References

  1. Barshtein G, Tamir I, Yedgar S (1998) Red blood cell rouleaux formation in dextran solution: dependence on polymer conformation. Eur Biophys J 27:177–181CrossRefGoogle Scholar
  2. Boublik T (1974) Statistical thermodynamics of convex molecule fluids. Mol Phys 27:1415–1427CrossRefGoogle Scholar
  3. Darawshe S, Rivas G, Minton AP (1993) Rapid and accurate microfractionation of the contents of small centrifuge tubes: application in the measurement of molecular weights of proteins via sedimentation equilibrium. Anal Biochem 209:130–135CrossRefGoogle Scholar
  4. de Gennes PG (1979) Scaling concepts in polymer physics. Cornell University Press, IthacaGoogle Scholar
  5. Ellis RJ (2001) Macromolecular crowding: obvious but underappreciated. Trends Biochem Sci 26:597–604CrossRefGoogle Scholar
  6. Fodeke AA, Minton AP (2010) Quantitative characterization of polymer–polymer, protein–protein, and polymer–protein interaction via tracer sedimentation equilibrium. J Phys Chem B 114:10876–10880CrossRefGoogle Scholar
  7. Fodeke AA, Minton AP (2011) Quantitative characterization of temperature-independent and temperature-dependent protein–protein interactions in highly-nonideal solutions. J Phys Chem B 115:11261–11268CrossRefGoogle Scholar
  8. Fulton AB (1982) How crowded is the cytoplasm? Cell 30:345–347CrossRefGoogle Scholar
  9. Homouz D, Perham M, Samiotakis A, Cheung MS, Stafhede WP (2008) Crowded, cell-like environment induces shape changes in aspherical protein. Proc Natl Acad Sci 105(33):11754–11759CrossRefGoogle Scholar
  10. Jiao M, Li H-T, Chen J, Minton AP, Liang Y (2010) Attractive protein–polymer interactions markedly alter the effect of macromolecular crowding on protein association equilibria. Biophys J 99:914–923CrossRefGoogle Scholar
  11. Kim YC, Mittal J (2013) Crowding induced entropy-enthalpy compensation in protein association equilibria. Phys Rev Lett 110:208102-1–208102-5Google Scholar
  12. Labowitz JL, Helfand E, Praestgaard E (1965) Scaled particle theory of fluid mixtures. J Chem Phys 43(3):774–779CrossRefGoogle Scholar
  13. Laurent TC, Killander JA (1964) Theory of gel filtration and its experimental verification. J Chromatogr A 14:317–330CrossRefGoogle Scholar
  14. McMillan WG, Mayer JE (1945) The statistical thermodynamics of multicomponent systems. J Chem Phys 13:276–305CrossRefGoogle Scholar
  15. Minton AP (1983) The effect of volume occupancy upon the thermodynamic activity of proteins: some biochemical consequences. Mol Cell Biochem 55:119–140CrossRefGoogle Scholar
  16. Minton AP (2001) The influence of macromolecular crowding and molecular confinement on biochemical reactions in physiological media. J Biol Chem 276:10577–10580CrossRefGoogle Scholar
  17. Mukherjee S, Waegele M, Chowdhury LG, Gai F (2009) Effect of macromolecular crowding on protein folding dynamics at the secondary structure level. J Mol Biol 393:227–236CrossRefGoogle Scholar
  18. Neu BJ, Wenby R, Meiselman HJ (2008) Effects of dextran molecular weight on red blood cell aggregation. Biophys J 95:3059–3065CrossRefGoogle Scholar
  19. Ogston AG (1958) The spaces in a uniform random suspension of fibers. Trans Faraday Soc 54:1754–1757CrossRefGoogle Scholar
  20. Ogston AG (1970) On the interaction of solute molecules with porous networks. J Phys Chem 74:668–669CrossRefGoogle Scholar
  21. Rad S, Gao J, Meiselman HJ, Baskurt OK, Neu B (2009) Depletion of high molecular weight dextran from the red cell surface measured by particle electrophoresis. Electrophoresis 30:450–456CrossRefGoogle Scholar
  22. Rivas G, Fernandez JA, Minton AP (1999) Direct observation of the self-association of dilute proteins in the presence of inert macromolecules at high concentration via tracer sedimentation equilibrium: theory, experiment, and biological significance. Biochemistry 38:9379–9388CrossRefGoogle Scholar
  23. Rosen J, Kim YC, Mittal J (2011) Modest protein-crowder attractive interaction can counteract enhancement of protein association by intermolecular excluded volume interaction. J Phys Chem 115:3683–3689CrossRefGoogle Scholar
  24. Zimmerman SB, Minton AP (1993) Macromolecular crowding: biochemical, biophysical, and physiological consequences. Annu Rev Biophys Biomol Struct 22:27–65CrossRefGoogle Scholar
  25. Zimmerman SB, Trach SO (1991) Estimation of macromolecule concentrations and excluded volume effects for the cytoplasm of Escherichia coli. J Mol Biol 222:599–620CrossRefGoogle Scholar
  26. Zorrilla S, Jiménez M, Lillo P, Rivas G, Minton AP (2004) Sedimentation equilibrium in a solution containing an arbitrary number of solute species at arbitrary concentrations: theory and application to concentrated solutions of ribonuclease. Biophys Chem 108:89–100CrossRefGoogle Scholar

Copyright information

© European Biophysical Societies' Association 2019

Authors and Affiliations

  1. 1.Department of ChemistryObafemi Awolowo UniversityIle-IfeNigeria

Personalised recommendations