Structure and disorder in the ribonuclease S-peptide probed by NMR residual dipolar couplings.

ABSTRACT: NMR residual dipolar couplings for the S-peptide of ribonuclease A aligned in C8E5/n-octanol liquid crystals are consistent with the presence of a native-like alpha-helix structure undergoing dynamic fraying. Residues 3-13, which correspond to the first alpha-helix of ribonuclease A, show couplings that become more negative at low temperature and in the presence of salt, conditions which stabilize alpha-helical structure in the S-peptide. By contrast, dipolar couplings from the N and C termini of the peptide are close to zero and remain nearly invariant with changes in solution conditions. Torsion angle dynamics simulations using a gradient of dihedral restraint bounds that increase from the center to the ends of the peptide reproduce the experimentally observed sequence dependence of dipo

SUBMITTER: Alexandrescu AT 

PROVIDER: S-EPMC2366913 | biostudies-literature | 2003 Oct

REPOSITORIES: biostudies-literature