Site‐Resolved Observation of Vibrational Energy Transfer Using a Genetically Encoded Ultrafast Heater |
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Authors: | Tobias Baumann Matthias Hauf Fabian Schildhauer Katharina B Eberl Patrick M Durkin Erhan Deniz Jan G Lffler Carlos G Acevedo‐Rocha Jelena Jaric Berta M Martins Holger Dobbek Jens Bredenbeck Nediljko Budisa |
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Institution: | Tobias Baumann,Matthias Hauf,Fabian Schildhauer,Katharina B. Eberl,Patrick M. Durkin,Erhan Deniz,Jan G. Löffler,Carlos G. Acevedo‐Rocha,Jelena Jaric,Berta M. Martins,Holger Dobbek,Jens Bredenbeck,Nediljko Budisa |
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Abstract: | Allosteric information transfer in proteins has been linked to distinct vibrational energy transfer (VET) pathways in a number of theoretical studies. Experimental evidence for such pathways, however, is sparse because site‐selective injection of vibrational energy into a protein, that is, localized heating, is required for their investigation. Here, we solved this problem by the site‐specific incorporation of the non‐canonical amino acid β‐(1‐azulenyl)‐l ‐alanine (AzAla) through genetic code expansion. As an exception to Kasha's rule, AzAla undergoes ultrafast internal conversion and heating after S1 excitation while upon S2 excitation, it serves as a fluorescent label. We equipped PDZ3, a protein interaction domain of postsynaptic density protein 95, with this ultrafast heater at two distinct positions. We indeed observed VET from the incorporation sites in the protein to a bound peptide ligand on the picosecond timescale by ultrafast IR spectroscopy. This approach based on genetically encoded AzAla paves the way for detailed studies of VET and its role in a wide range of proteins. |
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Keywords: | energy transfer mutagenesis non-canonical amino acids protein modification time-resolved spectroscopy |
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