Measuring the refolding of beta-sheets with different turn sequences on a nanosecond time scale.
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.
Chen
Rita P-Y
RP
Institutes of Chemistry and Atomic and Molecular Sciences, Academia Sinica, Taipei 115, Taiwan, Republic of China.
Huang
Joseph J-T
JJ
Chen
Hsin-Liang
HL
Jan
Howard
H
Velusamy
Marappan
M
Lee
Chung-Tien
CT
Fann
Wunshain
W
Larsen
Randy W
RW
Chan
Sunney I
SI
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