1
|
Uleanya KO, Anstöter CS, Dessent CEH. Photodissociative decay pathways of the flavin mononucleotide anion and its complexes with tryptophan and glutamic acid. Phys Chem Chem Phys 2023; 25:30697-30707. [PMID: 37934009 DOI: 10.1039/d3cp04359b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
Flavin mononucleotide (FMN) is a highly versatile biological chromophore involved in a range of biochemical pathways including blue-light sensing proteins and the control of circadian rhythms. Questions exist about the effect of local amino acids on the electronic properties and photophysics of the chromophore. Using gas-phase anion laser photodissociation spectroscopy, we have measured the intrinsic electronic spectroscopy (3.1-5.7 eV) and accompanying photodissociative decay pathways of the native deprotonated form of FMN, i.e. [FMN-H]- complexed with the amino acids tryptophan (TRP) and glutamic acid (GLU), i.e. [FMN-H]-·TRP and [FMN-H]-·GLU, to investigate the extent to which these amino acids perturb the electronic properties and photodynamics of the [FMN-H]- chromophore. The overall photodepletion profiles of [FMN-H]-·TRP and [FMN-H]-·GLU are similar to that of the monomer, revealing that amino acid complexation occurs without significant spectral shifting of the [FMN-H]- electronic excitations over this region. Both [FMN-H]-·TRP and [FMN-H]-·GLU are observed to decay by non-statistical photodecay pathways, although the behaviour of [FMN-H]-·TRP is closer to statistical fragmentation. Long-lived FMN excited states (triplet) are therefore relatively quenched when TRP binds to [FMN-H]-. Importantly, we find that [FMN-H]-, [FMN-H]-·TRP and [FMN-H]-·GLU all decay predominantly via electron detachment following photoexcitation of the flavin chromophore, with amino acid complexation appearing not to inhibit this decay channel. The strong propensity for electron detachment is attributed to excited-state proton transfer within FMN, with proton transfer from a ribose alcohol to the phosphate preceding electron detachment.
Collapse
Affiliation(s)
- Kelechi O Uleanya
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | - Cate S Anstöter
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
| | | |
Collapse
|
2
|
Uleanya KO, Dessent CEH. Investigating the mapping of chromophore excitations onto the electron detachment spectrum: photodissociation spectroscopy of iodide ion-thiouracil clusters. Phys Chem Chem Phys 2021; 23:1021-1030. [PMID: 33428696 DOI: 10.1039/d0cp05920j] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Laser photodissociation spectroscopy (3.1-5.7 eV) has been applied to iodide complexes of the non-native nucleobases, 2-thiouracil (2-TU), 4-thiouracil (4-TU) and 2,4-thiouracil (2,4-TU), to probe the excited states and intracluster electron transfer as a function of sulphur atom substitution. Photodepletion is strong for all clusters (I-·2-TU, I-·4-TU and I-·2,4-TU) and is dominated by electron detachment processes. For I-·4-TU and I-·2,4-TU, photodecay is accompanied by formation of the respective molecular anions, 4-TU- and 2,4-TU-, behaviour that is not found for other nucleobases. Notably, the I-·2TU complex does not fragment with formation of its molecular anion. We attribute the novel formation of 4-TU- and 2,4-TU- to the fact that these valence anions are significantly more stable than 2-TU-. We observe further similar behaviour for I-·4-TU and I-·2,4-TU relating to the general profile of their photodepletion spectra, since both strongly resemble the intrinsic absorption spectra of the respective uncomplexed thiouracil molecule. This indicates that the nucleobase chromophore excitations are determining the clusters' spectral profile. In contrast, the I-·2-TU photodepletion spectrum is dominated by the electron detachment profile, with the near-threshold dipole-bound excited state being the only distinct spectral feature. We discuss these observations in the context of differences in the dipole moments of the thionucleobases, and their impact on the coupling of nucleobase-centred transitions onto the electron detachment spectrum.
Collapse
Affiliation(s)
- Kelechi O Uleanya
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | | |
Collapse
|
3
|
Furlan C, Berenbeim JA, Dessent CEH. Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry. Molecules 2020; 25:molecules25225280. [PMID: 33198255 PMCID: PMC7696214 DOI: 10.3390/molecules25225280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/08/2020] [Accepted: 11/09/2020] [Indexed: 12/12/2022] Open
Abstract
Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.
Collapse
|
4
|
Cercola R, Uleanya KO, Dessent CEH. Electron detachment dynamics of the iodide-guanine cluster: does ionization occur from the iodide or from guanine? Mol Phys 2019. [DOI: 10.1080/00268976.2019.1679402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
5
|
Cercola R, Matthews E, Dessent CEH. Photoexcitation of Adenosine 5'-Triphosphate Anions in Vacuo: Probing the Influence of Charge State on the UV Photophysics of Adenine. J Phys Chem B 2017; 121:5553-5561. [PMID: 28521097 DOI: 10.1021/acs.jpcb.7b03435] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the first UV laser photodissociation spectra (4.0-5.8 eV) of gas-phase deprotonated adenosine 5'-triphosphate, diphosphate and monophosphate anions. The photodepletion spectra of these anions display strong absorption bands across the region of 4.6-5.2 eV, consistent with excitation of a primarily adenine-centered π-π* transition. The spectra appear insensitive to the charge of the species (i.e., the spectrum of [ATP-2H]2- closely resembles that of [ATP-H]-), while the spectral profile is affected to a greater extent by the variation of the molecular structure, i.e. the [AMP-H]- and [ADP-H]- photodepletion spectra display similar profiles while the [ATP-H]- spectrum is distinctive. The photodepletion cross-section also decreases for the ATP anions compared to both the AMP and ADP anions, reflecting a high intrinsic photostability of ATP versus both AMP and ADP. A range of photofragments are produced across the 4.0-5.8 eV spectral range for all of the ATP analogues studied. These fragments are primarily associated with fragmentation on the ground-state electronic surface, indicative of a statistical decay process where ultrafast decay is followed by ergodic dissociation. However, while the photofragments observed following photoexcitation of the monoanionic species, [AMP-H]- to [ADP-H]- to [ATP-H]- are entirely consistent with statistical decay, an additional group of photofragments are observed for the dianionic species, [ADP-2H]2- and [ATP-2H]2-, that we associate with electron detachment, and subsequent fragmentation of the resulting electron-detached photofragment. TDDFT calculations are presented to support the interpretation of the experimental data, and confirm that the electronic structure of the adenine moiety is relatively unperturbed by varying the overall charge.
Collapse
Affiliation(s)
- Rosaria Cercola
- Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K
| | - Edward Matthews
- Department of Chemistry, University of York , Heslington, York, YO10 5DD, U.K
| | | |
Collapse
|
6
|
Matthews E, Dessent CEH. Experiment and theory confirm that UV laser photodissociation spectroscopy can distinguish protomers formed via electrospray. Phys Chem Chem Phys 2017. [DOI: 10.1039/c7cp02817b] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Low-resolution UV spectroscopy within a laser-interfaced commercial mass spectrometer can be used to identify electrosprayed protomers of para-aminobenzoic acid (PABA).
Collapse
|
7
|
Matthews E, Dessent CEH. Locating the Proton in Nicotinamide Protomers via Low-Resolution UV Action Spectroscopy of Electrosprayed Solutions. J Phys Chem A 2016; 120:9209-9216. [DOI: 10.1021/acs.jpca.6b10433] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Edward Matthews
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | | |
Collapse
|
8
|
Synthesis, structures, molecular docking, cytotoxicity and bioimaging studies of two novel Zn(II) complexes. Eur J Med Chem 2016; 121:1-11. [DOI: 10.1016/j.ejmech.2016.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 04/11/2016] [Accepted: 05/05/2016] [Indexed: 01/24/2023]
|
9
|
Matthews E, Sen A, Yoshikawa N, Bergström E, Dessent CEH. UV laser photoactivation of hexachloroplatinate bound to individual nucleobases in vacuo as molecular level probes of a model photopharmaceutical. Phys Chem Chem Phys 2016; 18:15143-52. [DOI: 10.1039/c6cp01676f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
UV excitation of mass-selected hexachloroplatinate–nucleobase clusters provides detailed insight into the photophysics and photochemistry of a model DNA photopharmaceutical.
Collapse
Affiliation(s)
| | - Ananya Sen
- Department of Chemistry
- University of York
- York
- UK
| | | | | | | |
Collapse
|
10
|
Sen A, Matthews EM, Hou GL, Wang XB, Dessent CEH. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission. J Chem Phys 2015; 143:184307. [DOI: 10.1063/1.4935171] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Ananya Sen
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Edward M. Matthews
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Gao-Lei Hou
- Physical Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352, USA
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352, USA
| | | |
Collapse
|
11
|
Harvey AJA, Yoshikawa N, Wang JG, Dessent CEH. Communication: Evidence for dipole-bound excited states in gas-phase I− ⋅ MI (M = Na, K, Cs) anionic salt microclusters. J Chem Phys 2015; 143:101103. [DOI: 10.1063/1.4930919] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Andrew J. A. Harvey
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Naruo Yoshikawa
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Jin-Guo Wang
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | | |
Collapse
|
12
|
Sen A, Hou GL, Wang XB, Dessent CEH. Electron Detachment as a Probe of Intrinsic Nucleobase Dynamics in Dianion-Nucleobase Clusters: Photoelectron Spectroscopy of the Platinum II Cyanide Dianion Bound to Uracil, Thymine, Cytosine, and Adenine. J Phys Chem B 2015; 119:11626-31. [DOI: 10.1021/acs.jpcb.5b07108] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ananya Sen
- Department
of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Gao-Lei Hou
- Physical
Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352, United States
| | - Xue-Bin Wang
- Physical
Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352, United States
| | | |
Collapse
|
13
|
Harvey AJ, Sen A, Yoshikawa N, Dessent CE. UV laser spectroscopy of mass-selected ionic liquid building blocks in the gas-phase. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.06.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
14
|
Sen A, Dessent CEH. Communication: Photoactivation of nucleobase bound platinumIImetal complexes: Probing the influence of the nucleobase. J Chem Phys 2014; 141:241101. [DOI: 10.1063/1.4904259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Affiliation(s)
- Ananya Sen
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | | |
Collapse
|