Kinetics of folding of the all-beta sheet protein interleukin-1 beta.
The folding of the all-beta sheet protein, interleukin-1 beta, was studied with nuclear magnetic resonance (NMR) spectroscopy, circular dichroism, and fluorescence. Ninety percent of the beta structure present in the native protein, as monitored by far-ultraviolet circular dichroism, was attained within 25 milliseconds, correlating with the first kinetic phase determined by tryptophan and 1-anilinonaphthalene-8-sulfonate fluorescence. In contrast, formation of stable native secondary structure, as measured by quenched-flow deuterium-hydrogen exchange experiments, began after only 1 second. Results from the NMR experiments indicated the formation of at least two intermediates with half-lives of 0.7 to 1.5 and 15 to 25 seconds. The final stabilization of the secondary structure, however, occurs on a time scale much greater than 25 seconds. These results differ from previous results on mixed alpha helix-beta sheet proteins in which both the alpha helices and beta sheets were stabilized very rapidly (less than 10 to 20 milliseconds).
Varley
P
P
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health (NIH), Bethesda, MD 20892.
Gronenborn
A M
AM
Christensen
H
H
Wingfield
P T
PT
Pain
R H
RH
Clore
G M
GM
D002942:Circular Dichroism; D006860:Hydrogen Bonding; D007375:Interleukin-1 / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013050:Spectrometry, Fluorescence
D007375:Interleukin-1