Conformer-selective Photodynamics of TrpH+−H2O
The photodynamics of protonated tryptophan and its mono hydrated complex TrpH+−H2O has been revisited. A combination of steady-state IR and UV cryogenic ion spectroscopies with picosecond pump-probe photodissociation experiments sheds new lights on the deactivation processes of TrpH+ and conformer-s...
| Authors: | , , , , , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2023 |
| Country: | Argentina |
| Institution: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repository: | CONICET Digital (CONICET) |
| Language: | English |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/226761 |
| Online Access: | http://hdl.handle.net/11336/226761 |
| Access Level: | Open access |
| Keyword: | BIOMOLECULES CRYOGENIC ION SPECTROSCOPY HYDRATION IR AND UV PHOTODISSOCIATION PHOTOPHYSICS https://purl.org/becyt/ford/1.4 https://purl.org/becyt/ford/1 |
| Summary: | The photodynamics of protonated tryptophan and its mono hydrated complex TrpH+−H2O has been revisited. A combination of steady-state IR and UV cryogenic ion spectroscopies with picosecond pump-probe photodissociation experiments sheds new lights on the deactivation processes of TrpH+ and conformer-selected TrpH+−H2O complex, supported by quantum chemistry calculations at the DFT and coupled-cluster levels for the ground and excited states, respectively. TrpH+ excited at the band origin exhibits a transient of less than 100 ps, assigned to the lifetime of the excited state proton transfer (ESPT) structure. The two experimentally observed conformers of TrpH+−H2O have been assigned. A striking result arises from the conformer-selective photodynamics of TrpH+−H2O, in which a single water molecule inserted in between the ammonium and the indole ring hinders the barrierless ESPT reaction responsible for the ultra-fast deactivation process observed in the other conformer and in bare TrpH+. |
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