Fluorescence determination of tryptophan side-chain accessibility and dynamics in triple-helical collagen-like peptides.
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.
Simon-Lukasik
Kristine V
KV
Department of Food Science, Rutgers University, New Brunswick, New Jersey 08901, USA.
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
D000595:Amino Acid Sequence; D001483:Base Sequence; D003094:Collagen / Q000737:chemistry*; D005240:Feasibility Studies; D005454:Fluorescence Polarization / Q000379:methods*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014364:Tryptophan / Q000737:chemistry
C475913:Ac-(Gly-Pro-Hyp)3-Gly-Pro-Trp-(Gly-Pro-Hyp)4-Gly-Gly-CONH2; C475912:Ac-(Gly-Pro-Hyp)3-Gly-Trp-Hyp-(Gly-Pro-Hyp)4-Gly-Gly-CONH2; D010455:Peptides; D014364:Tryptophan; D003094:Collagen