NMR and CD studies of triple-helical peptides.
Triple-helix formation of the peptide (Pro-Hyp-Gly)10 was monitored by nmr and CD spectroscopy. The two-dimensional nmr spectra indicated that the Gly C alpha H and Pro C delta H proton resonances shift upfield in going from the nonhelical to helical form, while hydroxy-proline resonances are unchanged. The integrated areas of the helical and nonhelical resonances could be monitored in the one-dimensional nmr spectrum, and indicate that in the (Pro-Hyp-Gly)10 about 90% of the residues are in a defined triple-helical conformation. The introduction of a glycine to alanine substitution or the deletion of a single hydroxyproline residue in the stable triple-helical peptide (Pro-Hyp-Gly)10 still allows trimers to be formed, but the trimers show a substantial loss of triple helix and decreased thermal stability compared with (Pro-Hyp-Gly)10. Two computer models were generated for the Gly----Ala peptide, one with the Ala side chains packed inside the helix and the other with the region containing the alanines forming a beta-bend that loops out from the helix. The nmr data is more consistent with the latter model.
Brodsky
B
B
Department of Biochemistry, Robert Wood Johnson Medical School, Piscataway, New Jersey.
Li
M H
MH
Long
C G
CG
Apigo
J
J
Baum
J
J
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011487:Protein Conformation