Spectroscopy and dynamics of photoactive protein chromophores in complex environments

Project ID: 2228cd1373 (You will need this ID for your application)

UCL Lead department: Chemistry

Project Summary:

The overall objective of this PhD project is to deepen our understanding of the response of biologically relevant chromophores, specifically green fluorescent protein (GFP) chromophores, to the absorption of light and the effects of interactions with their surroundings. GFP and its variants are among the mostly widely used tools in biology for in vivo imaging and tracking. Their photophysical properties (e.g., fluorescence colour, quantum yield, Stokes shift) are exquisitely sensitive to the protein environment around the chromophore that lies at the heart of the protein. Therefore, GFP chromophores are excellent model systems for investigating how photophysical properties are influenced by interactions between a chromophore and its environment. Such understanding is key to achieving the general goal of obtaining a desired photoactive protein function from the rational design of its structure. This project will involve comparing the electronic structure and photodynamics of GFP chromophores in the gas-phase and in aqueous solution, with those confined in de novo macromolecular hosts, based on a-helical coil peptide barrels and tetrahelical protein maquettes designed to change the degree of confinement or binding-residue/site and thus the electrostatic environment of the protein pocket. Specifically, it will involve recording, analysing and interpreting, static and time-resolved photoelectron spectra, and femtosecond transient absorption spectra, of molecular anions in the gas-phase and solution-phase. It will involve using nanosecond and femtosecond lasers, anion velocity map imaging spectroscopy, liquid-microjet photoelectron spectroscopy, and femtosecond transient absorption spectroscopy. Experimental work will be carried out independently and as part of a team of researchers at UCL, Bristol, Imperial, and Oxford, who are working together on EPSRC Programme Grant EP/V026690/1 “Ultrafast Photochemical Dynamics in Complex Environments”. Candidates should have a keen interest in laser spectroscopy and photochemistry, and in working independently and as part of a team of researchers.