Direct observation of fast protein folding: the initial collapse of apomyoglobin.
The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiments on mutants and consideration of steady-state CD and fluorescence spectra indicate that the observed microsecond phase monitors assembly of an A x (H x G) helix subunit. Measurements at different viscosities indicate diffusive behavior even at low viscosities, in agreement with motions of a solvent-exposed protein during the initial collapse.
Ballew
R M
RM
School of Chemical Sciences and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, 61801, USA.
Sabelko
J
J
Gruebele
M
M
D000818:Animals; D001059:Apoproteins / Q000737:chemistry*; D002942:Circular Dichroism; D006736:Horses; D007700:Kinetics; D018482:Muscle, Skeletal / Q000737:chemistry; D009211:Myoglobin / Q000737:chemistry*; D017510:Protein Folding; D013050:Spectrometry, Fluorescence; D013055:Spectrophotometry, Infrared; D013696:Temperature
D001059:Apoproteins; D009211:Myoglobin; C010857:apomyoglobin