Protein pores can also be used as nanoreactors to study covalent chemistry at the single-molecule level. We have investigated a wide variety of chemistry in this way, including the formation and cleavage of arsenic-sulfur bonds, the photochemistry of 2-nitrobenzyl protecting groups, the photoisomerization of azobenzenes, the observation of polymerization one step at a time and a hydrogen-deuterium isotope effect.
New directions include the incorporation of unnatural amino acids into the α-hemolysin pore, with which to expand the range of chemistries that can be investigated, and the examination of catalysis. The nanoreactor technology is also being adapted to study complex reaction networks and molecular walkers at the single-molecule level.
Pulcu, G.S., Mikhailova, E., Choi, L.-S. and Bayley, H. Continuous observation of the stochastic motion of an individual small-molecule walker. Nature Nanotechnology 10, 76-83 (2015). DOI: 10.1038/NNANO.2014.264
Lee, J. and Bayley, H. A semisynthetic protein nanoreactor for single-molecule chemistry. Proc. Natl. Acad. Sci. USA 112, 13768-13773 (2015). www.pnas.org/cgi/doi/10.1073/pnas.1510565112
Bayley, H., Luchian, T., Shin, S.-H. and Steffensen, M.B. Single-molecule covalent chemistry in a protein nanoreactor, pp251-277, Chapter 10 in "Single Molecules and Nanotechnology", R. Rigler and H. Vogel, eds., Springer, Heidelberg (2008).