The effects of guanidine hydrochloride on the 'random coil' conformations and NMR chemical shifts of the peptide series GGXGG

Abstract

The effects of the commonly used denaturant guanidine hydrochloride (GuHCl) on the random coil conformations and NMR chemical shifts of the proteogenic amino acids have been characterized using the peptide series Ac-Gly-Gly-X-Gly-Gly-NH2. The φ angle-sensitive coupling constants, ROESY cross peak intensities and proline cis-trans isomer ratios of a representative subset of these peptides are unaffected by GuHCl, which suggests that the denaturant does not significantly perturb intrinsic backbone conformational preferences. A set of 3JHNHα values is presented which agree well with predictions of recently developed models of the random coil. We have also measured the chemical shifts of all 20 ..