This proposal seeks to provide fundamental insight into how, in the phytochrome photoreceptor (the plant growth and photoresponse control agent) and bacteriorhodopsin ( a light driven proton pump), protein structure relates to protein function and reactivity. The overall goal of this research is to study, using time-resolved infrared spectroscopy from picosecond to kilosecond time regimes, light-induced conformational changes and kinetic intermediates by following the dynamics of the protein amide I and II regions, carboxylic groups, specific amino acid (i.e. tryptophan and tyrosine) and protein photointermediates. In addition to the dynamic understanding of the interaction between light and the photosensitive bilitriene phytochrome, the investigatior will determine a) orientation and strenght of possible hydrogen bonds between the imine hydrogen and a nearby counter ion; and b) effects of a positive or negative charge near the C=N frequency shift upon protonation of both the bilitriene chromophore and the retinal Schiff's base chromophore. This proposal is also aimed at learning how the reversible photocontrol properties of phytochrome and bacteriorhodopsin can be used to produce light biosensors or photodevices.
