biostudies-literatureAstashkin AVNational Institute of Environmental Health SciencesNIEHS NIH HHSDivision of Molecular and Cellular BiosciencesNational Institute of General Medical SciencesNIGMS NIH HHS611-623https://www.ebi.ac.uk/biostudies/studies/S-EPMC11390318biostudies-literatureUnknown29(6)Nitric oxide synthases (NOSs), a family of flavo-hemoproteins with relatively rigid domains linked by flexible regions, require optimal FMN domain docking to the heme domain for efficient interdomain electron transfer (IET). To probe the FMN-heme interdomain docking, the magnetic dipole interactions between the FMN semiquinone radical (FMNH^•) and the low-spin ferric heme centers in oxygenase/FMN (oxyFMN) constructs of neuronal and inducible NOS (nNOS and iNOS, respectively) were measured using the relaxation-induced dipolar modulation enhancement (RIDME) technique. The FMNH^• RIDME data were analyzed using the mesoscale Monte Carlo calculations of conformational distributions of NOS, which were improved to account for the native degrees of freedom of the amino acid resJournal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic ChemistryAnalyzing the FMN-heme interdomain docking interactions in neuronal and inducible NOS isoforms by pulsed EPR experiments and conformational distribution modeling.PMC113903182041692P20GM130422P30ES032755P30 ES032755P20 GM130422R01 GM133973GM133973Astashkin AVGyawali YPZhang HJiang TFeng CfalseAnalyzing the FMN-heme interdomain docking interactions in neuronal and inducible NOS isoforms by pulsed EPR experiments and conformational distribution modeling.Nitric oxide synthases (NOSs), a family of flavo-hemoproteins with relatively rigid domains linked by flexible regions, require optimal FMN domain docking to the heme domain for efficient interdomain electron transfer (IET). To probe the FMN-heme interdomain docking, the magnetic dipole interactions between the FMN semiquinone radical (FMNH^•) and the low-spin ferric heme centers in oxygenase/FMN (oxyFMN) constructs of neuronal and inducible NOS (nNOS and iNOS, respectively) were measured using the relaxation-induced dipolar modulation enhancement (RIDME) technique. The FMNH^• RIDME data were analyzed using the mesoscale Monte Carlo calculations of conformational distributions of NOS, which were improved to account for the native degrees of freedom of the amino acid res2024-01-01T00:00:00Z2024 Sep2026-05-04T06:36:30.779Z2025-04-06T22:14:37.55ZS-EPMC113903183913677210.1007/s00775-024-02068-8