title: Measuring the refolding of beta-sheets with different turn sequences on a nanosecond time scale.
abstract: Whether turns play an active or passive role in protein folding remains a controversial issue at this juncture. Here we use a photolabile cage strategy in combination with laser-flash photolysis and photoacoustic calorimetry to study the effects of different turns on the kinetics of beta-hairpin refolding on a nanosecond time scale. This strategy opens up a temporal window to allow the observation of early kinetic events in the protein refolding process at ambient temperature and pH without interference from any denaturants. Our results provide direct evidence demonstrating that even a one-residue difference in the turn region can change the refolding kinetics of a peptide. This observation suggests an active role for turn formation in directing protein folding.
authors.affiliation: Institutes of Chemistry and Atomic and Molecular Sciences, Academia Sinica, Taipei 115, Taiwan, Republic of China.
authors.forename: Rita P-Y
authors.initials: RP
authors.lastname: Chen
authors.forename: Joseph J-T
authors.initials: JJ
authors.lastname: Huang
authors.forename: Hsin-Liang
authors.initials: HL
authors.lastname: Chen
authors.forename: Howard
authors.initials: H
authors.lastname: Jan
authors.forename: Marappan
authors.initials: M
authors.lastname: Velusamy
authors.forename: Chung-Tien
authors.initials: CT
authors.lastname: Lee
authors.forename: Wunshain
authors.initials: W
authors.lastname: Fann
authors.forename: Randy W
authors.initials: RW
authors.lastname: Larsen
authors.forename: Sunney I
authors.initials: SI
authors.lastname: Chan
mesh_terms: D000595:Amino Acid Sequence; D002151:Calorimetry / Q000379:methods*; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D017510:Protein Folding; D013696:Temperature