Nuclear magnetic resonance and circular dichroism studies of a triple-helical peptide with a glycine substitution.
The triple-helical conformation has the stringent amino acid sequence constraint that every third residue must be a glycine, (X-Y-Gly)n. We use nuclear magnetic resonance and circular dichroism to quantify the consequences of a substitution in the glycine position of a triple-helical peptide, and to enhance our understanding of interactions in this basic structural motif. A 30-residue peptide with a Gly----Ala change forms a stable trimer at a folding rate somewhat less than that of the unsubstituted peptide, and the substitution results in a marked decrease in thermal stability and a conformational perturbation of about 30% of the triple-helical structure. Two models were generated for this peptide, one with the alanine residues packed inside the triple helix and one with a looping out of the chain at the substitution site. Studies on the Gly----Ala peptide are useful in understanding connective tissue diseases which result from the substitution of one glycine residue in the triple-helix of fibrillar collagens.
Long
C G
CG
Department of Biochemistry, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854.
Li
M H
MH
Baum
J
J
Brodsky
B
B
D002942:Circular Dichroism; D005998:Glycine / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013696:Temperature
D010455:Peptides; D005998:Glycine