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Title: Electronic structure and dynamics of photoactive yellow protein chromophores
Author: Henley, Alice
ISNI:       0000 0004 9359 9859
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2020
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Photoactive yellow protein (PYP) is responsible for the negative phototactic response of Halorhodospira halophila to blue light. At the heart of PYP lies the anionic para-coumaric acid chromophore that initiates the response by photoisomerisation. The work presented in this thesis aimed to improve our understanding of the electronic structure and dynamics of the chromophore using photoelectron spectroscopy techniques and quantum chemistry calculations. Model chromophore analogues with molecular tethers hindering rotation about single or double bonds within the chromophore were studied in the gas phase with anion photoelectron spectroscopy. These studies aimed to investigate the role of torsional motion in controlling the competition between electronic relaxation processes, following photoexcitation in the range 400--310~nm. Evidence was found to suggest that single bond rotation about either site adjacent to the central C=C bond enabled efficient conversion from the first excited state to the ground state and locking the central C=C bond effectively turned off this conversion to the ground state. Later in this thesis, a protocol for simulating photodetachment from an anionic chromophore in solution is illustrated with phenolate – a molecular building block common to many biological molecules including the photoactive yellow protein chromophore. This computational approach is then applied to simulate electron detachment from a photoactive yellow protein chromophore in aqueous solution. These computational results are presented with, and provide molecular-level insight into, a liquid micro-jet x-ray photoelectron spectrum (recorded by collaborators). The energy required for the lowest energy electron detachment process is found to blue-shift dramatically upon solvation compared to the gas phase.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available