Title:	Computational chemistry studies of light-driven rotary molecular motors and photosensory proteins
DNr:	SNIC 2013/1-310
Project Type:	SNIC Medium Compute
Principal Investigator:	Bo Durbeej <bo.durbeej@liu.se>
Affiliation:	Linköpings universitet
Duration:	2013-12-01 – 2014-12-01
Classification:	10407 10405 10603
Keywords:

Abstract

This project involves computational chemistry studies for improving the efficiency of synthetic light-driven rotary molecular motors and for resolving a number of key issues concerning the mechanisms of photosensory proteins. Light-driven rotary molecular motors are molecules that can perform work by absorbing light energy and converting it to unidirectional rotary motion around a chemical bond. In this part of the project, we make use of quantum chemical methods to design motors exhibiting successively higher rotational frequencies, which is a key property for the use of these systems in nanotechnology. Furthermore, we also explore how the motors are best mounted on surfaces, which is another crucial step along the path toward full-fledged use of molecular motors as nanodevices. Present throughout all kingdoms of life, photosensory proteins like phytochromes regulate physiological processes in response to external light conditions. Although phytochromes were first detected more than fifty years ago, the basic chemical mechanisms underlying their biological functions remain poorly understood. This is largely a consequence of the fact that detailed structural data did not appear until 2005, when the first crystal structure of a phytochrome was reported. Together with a number of subsequent crystal structures, this pioneering effort provides guidance for ongoing experimental and computational work in the field. Using so-called QM/MM methods that combine quantum and classical mechanics, this project will establish how phytochromes are converted from an inactive state to a biologically active state. Furthermore, the project will uncover how phytochromes tune their light absorption to facilitate this conversion. These objectives offer great promise to fill long-standing gaps in the understanding of how phytochromes operate.