{"doi":"10.1002/anie.202518264","title":"Dynamics and Mechanism of Off‐ to On‐Switching in Dreiklang a Decoupled Reversibly Switchable Fluorescent Protein","abstract":"Dreiklang is a reversibly switchable (rs) fluorescent protein (FP) with a unique off-state, a UV absorbing hydrated form of the typical FP chromophore. Here we report ultrafast dynamics of the off- to on-state transition in Dreiklang using complementary ultrafast optical and vibrational transient absorption to resolve chromophore driven protein structural dynamics. This approach allows observation of the real-time response in a protein to bond breaking and forming events. The excited electronic state decays in a nonsingle exponential fashion in tens to hundreds of picoseconds, undergoing photodehydration with a yield of several per-cent. The primary photoproduct formed is identified as the cis protonated form of the FP chromophore, initially in a perturbed H-bonded environment. This primary product relaxes on a few microseconds timescale by a mechanism involving changes to a glutamic acid residue and modifications of the amide backbone, possibly involving a carbonyl to imine tautomerization. The temporal and spectral resolution of Dreiklang's photodehydration provides data against which to test quantum chemical calculations of reaction dynamics in proteins and suggests a route to modifying and potentially enhancing its photoswitching properties.","journal":"Angewandte Chemie International Edition","year":2025,"id":548457,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9549,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":928015,"name":"YongLe He","orcid":"0000-0001-7274-535X","position":1,"is_corresponding":false},{"id":1442153,"name":"Danielle Rosenberger","orcid":null,"position":2,"is_corresponding":false},{"id":569692,"name":"Gregory M. Greetham","orcid":"0000-0002-1852-3403","position":3,"is_corresponding":false},{"id":1410785,"name":"Partha Malakar","orcid":"0000-0001-6874-7010","position":4,"is_corresponding":false},{"id":409729,"name":"András Lukács","orcid":"0000-0001-8841-9823","position":5,"is_corresponding":false},{"id":22118,"name":"Peter J. Tonge","orcid":"0000-0003-1606-3471","position":6,"is_corresponding":false},{"id":409734,"name":"Stephen R. Meech","orcid":"0000-0001-5561-2782","position":7,"is_corresponding":false},{"id":1254723,"name":"Anam Fatima","orcid":"0000-0003-2388-4390","position":0,"is_corresponding":true}],"reference_count":28,"raw_metadata":null,"created_at":"2026-07-19T02:53:58.530220Z","pmid":"41215619","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}