title: Nuclear magnetic resonance and circular dichroism studies of a triple-helical peptide with a glycine substitution.
abstract: 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.
authors.affiliation: Department of Biochemistry, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854.
authors.forename: C G
authors.initials: CG
authors.lastname: Long
authors.forename: M H
authors.initials: MH
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Baum
authors.forename: B
authors.initials: B
authors.lastname: Brodsky
mesh_terms: D002942:Circular Dichroism; D005998:Glycine / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D013696:Temperature
chemical_list: D010455:Peptides; D005998:Glycine