Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents
UV radiation from the sun is strongly absorbed by DNA, and the resulting electronic excited states can lead to the formation of mutagenic photoproducts. Decades of research have brought to light the excited-state dynamics of single RNA and DNA nucleobases, but questions remain about the nature of ex...
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Montana State University - Bozeman, College of Letters & Science
2017
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ftmontanastateu:oai:scholarworks.montana.edu:1/15063 2023-05-15T13:54:59+02:00 Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents Beckstead, Ashley Ann Chairperson, Graduate Committee: Robert Walker 2017 application/pdf https://scholarworks.montana.edu/xmlui/handle/1/15063 en eng Montana State University - Bozeman, College of Letters & Science https://scholarworks.montana.edu/xmlui/handle/1/15063 Copyright 2017 by Ashley Ann Beckstead Ultraviolet radiation Dynamics Charge transfer Laser spectroscopy DNA Indole Dissertation 2017 ftmontanastateu 2022-06-06T07:28:49Z UV radiation from the sun is strongly absorbed by DNA, and the resulting electronic excited states can lead to the formation of mutagenic photoproducts. Decades of research have brought to light the excited-state dynamics of single RNA and DNA nucleobases, but questions remain about the nature of excited states accessed in DNA strands. In this thesis, I present ultrafast spectroscopic observations of photoinduced electron transfer from the oxidatively damaged bases, 8-oxo-7,8-dihydro-2'-deoxyguanosine, 5-hydroxy-2'-deoxycytidine and 5-hydroxy-2'-deoxyuridine, to adenine in three dinucleotides. The results reveal that charge transfer states are formed on a timescale faster than our instrumental resolution (<0.5 ps), and back electron transfer efficiently returns the excited-state population to the ground state on timescales from tens to hundreds of ps. In addition to recent spectroscopic observations of charge transfer state species in DNA by other groups, our results have augmented understanding of the long-lived transient signals observed in DNA strands. The observation of photoinduced electron transfer in these oxidatively damaged nucleobases also supports a recent proposal regarding the role of oxidative products in pre-RNA catalysis. I discuss these observations in the contexts of fundamental DNA excited-state dynamics and prebiotic chemical evolution. In this thesis, I also present the first ultrafast spectroscopic investigation of violacein, a pigment isolated from Antarctic bacteria. Despite claims for the photoprotective role of this pigment, there has never been a spectroscopic analysis of excited-state deactivation in violacein. Emission spectra, fluorescence quantum yields and excited-state lifetimes of violacein in various solvents were measured for the first time. Both the fluorescence quantum yield and excited-state lifetime of violacein increase in increasingly viscous solvents, suggesting a large-scale motion mediates excited-state deactivation. I compare these results to similar observations ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Montana State University (MSU): ScholarWorks Antarctic |
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Montana State University (MSU): ScholarWorks |
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English |
topic |
Ultraviolet radiation Dynamics Charge transfer Laser spectroscopy DNA Indole |
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Ultraviolet radiation Dynamics Charge transfer Laser spectroscopy DNA Indole Beckstead, Ashley Ann Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents |
topic_facet |
Ultraviolet radiation Dynamics Charge transfer Laser spectroscopy DNA Indole |
description |
UV radiation from the sun is strongly absorbed by DNA, and the resulting electronic excited states can lead to the formation of mutagenic photoproducts. Decades of research have brought to light the excited-state dynamics of single RNA and DNA nucleobases, but questions remain about the nature of excited states accessed in DNA strands. In this thesis, I present ultrafast spectroscopic observations of photoinduced electron transfer from the oxidatively damaged bases, 8-oxo-7,8-dihydro-2'-deoxyguanosine, 5-hydroxy-2'-deoxycytidine and 5-hydroxy-2'-deoxyuridine, to adenine in three dinucleotides. The results reveal that charge transfer states are formed on a timescale faster than our instrumental resolution (<0.5 ps), and back electron transfer efficiently returns the excited-state population to the ground state on timescales from tens to hundreds of ps. In addition to recent spectroscopic observations of charge transfer state species in DNA by other groups, our results have augmented understanding of the long-lived transient signals observed in DNA strands. The observation of photoinduced electron transfer in these oxidatively damaged nucleobases also supports a recent proposal regarding the role of oxidative products in pre-RNA catalysis. I discuss these observations in the contexts of fundamental DNA excited-state dynamics and prebiotic chemical evolution. In this thesis, I also present the first ultrafast spectroscopic investigation of violacein, a pigment isolated from Antarctic bacteria. Despite claims for the photoprotective role of this pigment, there has never been a spectroscopic analysis of excited-state deactivation in violacein. Emission spectra, fluorescence quantum yields and excited-state lifetimes of violacein in various solvents were measured for the first time. Both the fluorescence quantum yield and excited-state lifetime of violacein increase in increasingly viscous solvents, suggesting a large-scale motion mediates excited-state deactivation. I compare these results to similar observations ... |
author2 |
Chairperson, Graduate Committee: Robert Walker |
format |
Doctoral or Postdoctoral Thesis |
author |
Beckstead, Ashley Ann |
author_facet |
Beckstead, Ashley Ann |
author_sort |
Beckstead, Ashley Ann |
title |
Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents |
title_short |
Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents |
title_full |
Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents |
title_fullStr |
Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents |
title_full_unstemmed |
Excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged DNA and deactivation of violacein in viscous solvents |
title_sort |
excited-state dynamics of biological molecules in solution: photoinduced charge transfer in oxidatively damaged dna and deactivation of violacein in viscous solvents |
publisher |
Montana State University - Bozeman, College of Letters & Science |
publishDate |
2017 |
url |
https://scholarworks.montana.edu/xmlui/handle/1/15063 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
https://scholarworks.montana.edu/xmlui/handle/1/15063 |
op_rights |
Copyright 2017 by Ashley Ann Beckstead |
_version_ |
1766261205276557312 |