Open AccessToward solving the folding pathway of barnase: the complete backbone 13C, 15N, and 1H NMR assignments of its pH-denatured state.
Author(s) -
Vickery L. Arcus,
Stéphane Vuilleumier,
Stefan Freund,
Mark Bycroft,
Alan R. Fersht
Publication year - 1994
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.91.20.9412
Subject(s) - barnase , phi value analysis , chemistry , heteronuclear molecule , nuclear overhauser effect , folding (dsp implementation) , protein folding , crystallography , nuclear magnetic resonance spectroscopy , random coil , downhill folding , stereochemistry , circular dichroism , biochemistry , ribonuclease , rna , electrical engineering , gene , engineering
The structures of the major folding intermediate, the transition state for folding, and the folded state of barnase have been previously characterized. We now add a further step toward a complete picture of the folding of barnase by reporting the backbone 15N, 13C, and 1H NMR assignments for barnase unfolded at pH 1.8 and 30 degrees C. These assignments, which were obtained from a combination of heteronuclear magnetization transfer and backbone triple-resonance NMR experiments, constitute the first stage in the structural characterization of this denatured state by NMR. Interresidue nuclear Overhauser effect contacts and deviations from 1H random-coil chemical shifts provide evidence for stable residual structure. The structured regions span residues in the native protein that contain its major alpha-helix and central strands of the beta-sheet. Earlier experiments have shown that these regions are predominantly intact in the major folding intermediate and that their docking is partly rate determining in folding.