biostudies-literatureVasilev CNational Defense Education ProgramUniversity of Illinois at Urbana-ChampaignEuropean Research CouncilGrantham Foundation for the Protection of the EnvironmentUniversity of SheffieldNational Institutes of HealthRoyal SocietyNIGMS NIH HHSBiotechnology and Biological Sciences Research CouncilNational Science Foundation20019-20032https://www.ebi.ac.uk/biostudies/studies/S-EPMC11273609biostudies-literatureUnknown146(29)Small, diffusible redox proteins play an essential role in electron transfer (ET) in respiration and photosynthesis, sustaining life on Earth by shuttling electrons between membrane-bound complexes via finely tuned and reversible interactions. Ensemble kinetic studies show transient ET complexes form in two distinct stages: an "encounter" complex largely mediated by electrostatic interactions, which subsequently, through subtle reorganization of the binding interface, forms a "productive" ET complex stabilized by additional hydrophobic interactions around the redox-active cofactors. Here, using single-molecule force spectroscopy (SMFS) we dissected the transient ET complexes formed between the photosynthetic reaction center-light harvesting complex 1 (RC-LH1) of <i>Rhodobacter sphaeroides<Journal of the American Chemical SocietySingle-Molecule Detection of the Encounter and Productive Electron Transfer Complexes of a Photosynthetic Reaction Center.PMC11273609R01-GM141298MCB- 1942763BB/V006630/1URF\R1\191548HQ0034-21-S-F001BB/M000265/1854126R01 GM141298Hunter CNMayneord GEVasilev CBowie AGMJohnson MPHitchcock APogorelov TVMartin ECSingharoy ANguyen JfalseSingle-Molecule Detection of the Encounter and Productive Electron Transfer Complexes of a Photosynthetic Reaction Center.Small, diffusible redox proteins play an essential role in electron transfer (ET) in respiration and photosynthesis, sustaining life on Earth by shuttling electrons between membrane-bound complexes via finely tuned and reversible interactions. Ensemble kinetic studies show transient ET complexes form in two distinct stages: an "encounter" complex largely mediated by electrostatic interactions, which subsequently, through subtle reorganization of the binding interface, forms a "productive" ET complex stabilized by additional hydrophobic interactions around the redox-active cofactors. Here, using single-molecule force spectroscopy (SMFS) we dissected the transient ET complexes formed between the photosynthetic reaction center-light harvesting complex 1 (RC-LH1) of <i>Rhodobacter sphaeroides<2024-01-01T00:00:00Z2024 Jul2026-06-01T10:03:04.906Z2025-04-19T11:32:19.257ZS-EPMC112736093899110810.1021/jacs.4c03913