A Single‐Molecule Approach to Explore the Role of the Solvent Environment in Protein Folding

This chapter first introduces the technique of single‐molecule force spectroscopy using the atomic force microscope (AFM). It presents the two modes of operation of the AFM for the study of protein folding: force‐extension and force‐clamp spectroscopy. Next, it presents recent work which has used single‐molecule force spectroscopy to explore the role of the solvent environment in protein folding. It looks at the role of denaturing and protecting osmolytes in determining the mechanical stability of a range of different proteins. Further, the chapter explores the role of hydrogen bonds in the surrounding solvent environment, followed by the hydrophobic collapse of an extended protein. Next, it presents results which have explored the role of solvent molecules in the complete unfolding and refolding pathway of a protein. Finally, the chapter provides a discussion on the future perspectives and challenges for this emerging field in single‐molecule protein folding.