High-Resolution Spectroscopy and Selective Photoresponse of Cryogenically Cooled Green Fluorescent Protein Chromophore Anions

By time-resolved action spectroscopy of cryogenically cooled molecular ions, we have achieved a remarkable vibrational resolution in the photoresponse of the deprotonated green fluorescent protein (GFP) chromophore, a key molecular unit in the bioimaging of living cells. We define four characteristi...

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Bibliographic Details
Published in:The journal of physical chemistry letters 2023-07, Vol.14 (28), p.6395-6401
Main Authors: Andersen, Lars H., Rasmussen, Anne P., Pedersen, Henrik B., Beletsan, Oleg B., Bochenkova, Anastasia V.
Format: Article
Language:English
Subjects:
Physical Insights into Materials and Molecular Properties
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Summary:By time-resolved action spectroscopy of cryogenically cooled molecular ions, we have achieved a remarkable vibrational resolution in the photoresponse of the deprotonated green fluorescent protein (GFP) chromophore, a key molecular unit in the bioimaging of living cells. We define four characteristic spectral regions of the S0–S1 band with competing electronic and nuclear decay channels. We determine the energy barrier toward internal conversion to be ∼250 cm–1. This inhibits internal conversion and hence statistical fragmentation near the S0–S1 band origin, which is identified at 481.51 ± 0.15 nm (20768 ± 6 cm–1). The origin is red-shifted by only 221 cm–1 compared to that of wild-type GFP at 77 K. This, together with a striking agreement between the vibronic profiles of the protein and its chromophore, suggests their similar photophysics. In combination with theory, the data reveal the coexistence of mutually energy-borrowing mechanisms between nuclei and electrons mediated by specific vibrational modes.
ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.3c01452