Dataset Information

Fluorescence determination of tryptophan side-chain accessibility and dynamics in triple-helical collagen-like peptides.

ABSTRACT: We report tryptophan fluorescence measurements of emission intensity, iodide quenching, and anisotropy that describe the environment and dynamics at X and Y sites in stable collagen-like peptides of sequence (Gly-X-Y)(n). About 90% of tryptophans at both sites have similar solvent exposed fluorescence properties and a lifetime of 8.5-9 ns. Analysis of anisotropy decays using an associative model indicates that these long lifetime populations undergo rapid depolarizing motion with a 0.5 ns correlation time; however, the extent of fast motion at the Y site is considerably less than the essentially unrestricted motion at the X site. About 10% of tryptophans at both sites have a shorter ( approximately 3 ns) lifetime indicating proximity to a protein quenching group; these minor populations are immobile on the peptide surface, depolarizing only by overall trimer rotation. Iodide quenching indicates that tryptophans at the X site are more accessible to solvent. Side chains at X sites are more solvent accessible and considerably more mobile than residues at Y sites and can more readily fluctuate among alternate intermolecular interactions in collagen fibrils. This fluorescence analysis of collagen-like peptides lays a foundation for studies on the structure, dynamics, and function of collagen and of triple-helical junctions in gelatin gels.

SUBMITTER: Simon-Lukasik KV

PROVIDER: S-EPMC1302630 | biostudies-literature | 2003 Jan

REPOSITORIES: biostudies-literature

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Fluorescence determination of tryptophan side-chain accessibility and dynamics in triple-helical collagen-like peptides.

Simon-Lukasik Kristine V KV Persikov Anton V AV Brodsky Barbara B Ramshaw John A M JA Laws William R WR Alexander Ross J B JB Ludescher Richard D RD

Biophysical journal 20030101 1

We report tryptophan fluorescence measurements of emission intensity, iodide quenching, and anisotropy that describe the environment and dynamics at X and Y sites in stable collagen-like peptides of sequence (Gly-X-Y)(n). About 90% of tryptophans at both sites have similar solvent exposed fluorescence properties and a lifetime of 8.5-9 ns. Analysis of anisotropy decays using an associative model indicates that these long lifetime populations undergo rapid depolarizing motion with a 0.5 ns correl ...[more]

PMID: 12524302

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Project description:Helices are the most extensively studied secondary structures formed by ?-peptide foldamers. Among the five known ?-peptide helices, the 12-helix is particularly interesting because the internal hydrogen bond orientation and macrodipole are analogous to those of ?-peptide helices (?-helix and 3(10)-helix). The ?-peptide 12-helix is defined by i, i+3 C?O···H-N backbone hydrogen bonds and promoted by ?-residues with a five-membered ring constraint. The 12-helical scaffold has been used to generate ?-peptides with specific biological functions, for which diverse side chains must be properly placed along the backbone and, upon folding, properly arranged in space. Only two crystal structures of 12-helical ?-peptides have previously been reported, both for homooligomers of trans-2-aminocyclopentanecarboxylic acid (ACPC). Here we report five additional crystal structures of 12-helical ?-peptides, all containing residues that bear side chains. Four of the crystallized ?-peptides include trans-4,4-dimethyl-2-aminocyclopentanecarboxylic acid (dm-ACPC) residues, and the fifth contains a ?(3)-hPhe residue. These five ?-peptides adopt fully folded 12-helical conformations in the solid state. The new crystal structures, along with previously reported data, allow a detailed characterization of the 12-helical conformation; average backbone torsion angles of ?-residues and helical parameters are derived. These structural parameters are found to be similar to those for i, i+3 C?O···H-N hydrogen-bonded helices formed by other peptide backbones generated from ?- and/or ?-amino acids. The similarity between the conformational behavior of dm-ACPC and ACPC is consistent with previous NMR-based conclusions that 4,4-disubstituted ACPC derivatives are compatible with 12-helical folding. In addition, our data show how a ?(3)-residue is accommodated in the 12-helix, thus enhancing understanding of the diverse conformational behavior of this flexible class of ?-amino acids.

Dataset Information

Fluorescence determination of tryptophan side-chain accessibility and dynamics in triple-helical collagen-like peptides.

Publications

Fluorescence determination of tryptophan side-chain accessibility and dynamics in triple-helical collagen-like peptides.

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