Picosecond conformational transition and equilibration of a cyclic peptide.
Ultrafast IR spectroscopy is used to monitor the nonequilibrium backbone dynamics of a cyclic peptide in the amide I vibrational range with picosecond time resolution. A conformational change is induced by means of a photoswitch integrated into the peptide backbone. Although the main conformational change of the backbone is completed after only 20 ps, the subsequent equilibration in the new region of conformational space continues for times >16 ns. Relaxation and equilibration processes of the peptide backbone occur on a discrete hierarchy of time scales. Albeit possessing only a few conformational degrees of freedom compared with a protein, the peptide behaves highly nontrivially and provides insights into the complexity of fast protein folding.
Bredenbeck
Jens
J
Universität Zürich, Physikalisch Chemisches Institut, Winterthurer Strasse 190, Switzerland.
Helbing
Jan
J
Sieg
Arne
A
Schrader
Tobias
T
Zinth
Wolfgang
W
Renner
Christian
C
Behrendt
Raymond
R
Moroder
Luis
L
Wachtveitl
Josef
J
Hamm
Peter
P
D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared
D010456:Peptides, Cyclic