{"doi":"10.1021/acs.jpcb.5c00082","title":"Application of Amber Suppression To Study the Role of Tyr M210 in Electron Transfer in <i>Rhodobacter sphaeroides</i> Photosynthetic Reaction Centers","abstract":"The initial light-induced electron transfer (ET) steps in the bacterial photosynthetic reaction center (RC) have been extensively studied and provide a paradigm for connecting structure and function. Although RCs have local pseudo- C 2 symmetry, ET only occurs along the A branch of chromophores. Tyrosine M210 is a key symmetry-breaking residue adjacent to bacteriochlorophyll B A that bridges the primary electron donor P and the bacteriopheophytin acceptor H A . We used amber suppression to incorporate phenylalanine variants with different electron-withdrawing/-donating capabilities at the position M210. X-ray data generally reveal no appreciable structural changes due to the mutations. P* decay and P + H A – formation are multiexponential (∼2 to 9, ∼10 to 60, and ∼100 to 300 ps) and temperature dependent. The 1020 nm transient-absorption band of P + B A – is barely resolved for a few variants at 295 K and for none at 77 K. The results indicate a change from two-step ET for wild-type RCs to the dominance of one-step superexchange ET for the mutants. Resonance Stark spectroscopy reveals that the free energy of P + B A – changes by −57 to +66 meV among the phenylalanine variants. Because P + B A – apparently lies above P* in all phenylalanine variants, the perturbations primarily affect the energy denominator for superexchange mixing. The findings deepen insight into primary ET in the bacterial RC.","journal":"The Journal of Physical Chemistry B","year":2025,"id":540735,"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":2,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.956,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"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":1359833,"name":"Kaitlyn M. Faries","orcid":"0000-0003-1777-7716","position":1,"is_corresponding":false},{"id":1359834,"name":"Nikki Cecil M. Magdaong","orcid":"0000-0003-3550-8288","position":2,"is_corresponding":false},{"id":272544,"name":"Irimpan I. Mathews","orcid":"0000-0001-6254-3519","position":3,"is_corresponding":false},{"id":1359835,"name":"Jared Bryce Weaver","orcid":"0000-0002-3823-422X","position":4,"is_corresponding":false},{"id":1071537,"name":"Jacob M. Kirsh","orcid":"0000-0002-1444-2913","position":5,"is_corresponding":false},{"id":1359836,"name":"Dewey Holten","orcid":"0000-0003-3639-6345","position":6,"is_corresponding":false},{"id":1359837,"name":"Christine Kirmaier","orcid":"0000-0003-1825-4546","position":7,"is_corresponding":false},{"id":272545,"name":"Steven G. Boxer","orcid":"0000-0001-9167-4286","position":8,"is_corresponding":false},{"id":1196712,"name":"Khoi Tran","orcid":"0000-0001-5009-8956","position":0,"is_corresponding":true}],"reference_count":105,"raw_metadata":null,"created_at":"2026-07-19T02:52:42.901627Z","pmid":"40134359","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":[]}