Open AccessComplementarity of ensemble and single-molecule measures of protein motion: A relaxation dispersion NMR study of an enzyme complex
Author(s) -
Pramodh Vallurupalli,
Lewis E. Kay
Publication year - 2006
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0602310103
Subject(s) - chemistry , flavin group , flavin adenine dinucleotide , oxidoreductase , electron transfer , förster resonance energy transfer , protein dynamics , flavin mononucleotide , molecule , fluorescence , acceptor , relaxation (psychology) , crystallography , molecular dynamics , cofactor , photochemistry , computational chemistry , enzyme , biochemistry , biology , physics , organic chemistry , condensed matter physics , quantum mechanics , neuroscience
Single-molecule fluorescence experiments have shown that the conformation of the complex betweenEscherichia coli general NAD(P)H:flavin oxidoreductase (FRE) and flavin adenine dinucleotide (FAD) fluctuates over a range of timescales between 10−4 and 1 s. Here we use15 N and13 C relaxation dispersion NMR methods to study millisecond-timescale dynamics in the complex. In this time regime, the protein is extremely flexible, with residues that undergo conformational exchange located throughout the molecule. Three distinct regions of dynamics are quantified, with two of them involving residues making contact to the donor (Tyr-35) and acceptor (FAD) sites that participate in the electron transfer reaction monitored in single-molecule experiments. Modulation of the donor–acceptor distance through these conformational exchange processes, occurring with rates of ≈400 and 1,200 s−1 (22°C), affects the rate of electron transfer and partially accounts for the range of the observed dynamics monitored in the fluorescence experiments.