A molecular motor can produce directional motion in cycles of conformational changes, driven by chemical energy and/or light energy; and molecules that are not normally regarded as motors may also have this capability. To decipher fundamental mechanisms of energy transduction, we investigate two cases using theory and computation. The first is one of the crowded chiral alkene motors pioneered by Ben Feringa et al. and features light-driven unidirectional rotation by consecutive E–Z photoisomerization and thermal helix inversion. We present a multilevel model for the full rotation cycle. Our model uses surface-hopping molecular dynamics to describe the excited state dynamics of the molecule on nanosecond timescale, and classical molecular dynamics simulations to describe the thermal helix inversion that occurs on microsecond timescale. The second case centers on the experimental observation that some enzymes exhibit enhanced diffusion when exposed to substrate, and chemotaxis when exposed to substrate gradients. Several potential mechanisms have been proposed for these phenomena. We describe a theoretical analysis that constrains the range of plausible mechanisms for the transduction of chemical energy to motion in enzymes.

Mechanisms for the transduction of light and chemical energy into molecular motion

2019 Fall National Meeting

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