Prof. Anand Yethiraj

LE STUDIUM Guest Research Fellow

From

Department of Physics and Physical Oceanography, University of Newfoundland - CA

In residence at

Molecular Biophysics Center (CBM) / CNRS - FR

Host scientist

Prof. Francesco Piazza

PROJECT

Macromolecular crowding: a physicist's perspective on understanding molecular motions in the complex environment of a living cell

The premise of this work is based on recent research that indicates that enzymes are physically propelled when they are catalyzing a reaction[1]. During the catalysis process, enzymes catalyze (i.e. greatly enhance the speed of) the transformation of “substrate” molecules into product species. Enzymes are seen to exhibit both chemotaxis and anti-chemotaxis[2], i.e., they exhibit motion either upward or downward, along or against the substrate concentration gradient. Follow-up work in groups in the USA[3], South Korea[4] and Spain[5] appear to confirm the observation, of enhanced motions, while other research suggests that this observation might simply be a fluorescence artifact[6]. We pursued (and continue to pursue) enzyme-nanoparticle attachment chemistry for multiple reasons:

1. Using the nanoparticle as probe, we look for enhanced motions in the presence of substrate without fluorescence measurements, thus avoiding possible artifacts.
2. The resulting functionalized nanoparticles would be “active nano-motors” that would have very fascinating non-equilibrium properties and would serve as an excellent model system for non-equilibrium soft matter.
3. These active nanoparticles can serve as active crowders in mimics of the crowded cellular environment.

[1] Riedel, C., Gabizon, R., Wilson, C. A. M., Hamadani, K., Tsekouras, K., Marqusee, S. et al. (2015). The heat released during catalytic turnover enhances the diffusion of an enzyme. Nature, 517(7533), 227.
[2] Jee, A.-Y., Dutta, S., Cho, Y.-K., Tlusty, T., & Granick, S. (2018). Enzyme leaps fuel antichemotaxis. Proceedings of the National Academy of Sciences, 115(1), 14-18.
[3] Muddana, H. S., Sengupta, S., Mallouk, T. E., Sen, A., & Butler, P. J. (2010). Substrate catalysis enhances single-enzyme diffusion. Journal of the American Chemical Society, 132(7), 2110-2111.
[4] Jee, A.-Y., Cho, Y.-K., Granick, S., & Tlusty, T. (2018). Catalytic enzymes are active matter. Proceedings of the National Academy of Sciences, 115(46), E10812-E10821.
[5] Patiño, T., Feiner-Gracia, N., Arqué, X., Miguel-López, A., Jannasch, A., Stumpp, T. et al. (2018). Influence of enzyme quantity and distribution on the self-propulsion of non-Janus urease powered micromotors. Journal of the American Chemical Society.
[6] Günther, J.-P., Börsch, M., & Fischer, P. (2018). Diffusion measurements of swimming enzymes with fluorescence correlation spectroscopy. Accounts of chemical research, 51(9), 1911-1920.