title: Microsecond hydrophobic collapse in the folding of Escherichia coli dihydrofolate reductase, an alpha/beta-type protein.
abstract: Using small-angle X-ray scattering combined with a continuous-flow mixing device, we monitored the microsecond compaction dynamics in the folding of Escherichia coli dihydrofolate reductase, an alpha/beta-type protein. A significant collapse of the radius of gyration from 30 A to 23.2 A occurs within 300 micros after the initiation of refolding by a urea dilution jump. The subsequent folding after the major chain collapse occurs on a considerably longer time-scale. The protein folding trajectories constructed by comparing the development of the compactness and the secondary structure suggest that the specific hydrophobic collapse model rather than the framework model better explains the experimental observations. The folding trajectory of this alpha/beta-type protein is located between those of alpha-helical and beta-sheet proteins, suggesting that native structure determines the folding landscape.
authors.affiliation: Protein Design Research Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan. munehito-arai@aist.go.jp
authors.forename: Munehito
authors.initials: M
authors.lastname: Arai
authors.forename: Elena
authors.initials: E
authors.lastname: Kondrashkina
authors.forename: Can
authors.initials: C
authors.lastname: Kayatekin
authors.forename: C Robert
authors.initials: CR
authors.lastname: Matthews
authors.forename: Masahiro
authors.initials: M
authors.lastname: Iwakura
authors.forename: Osman
authors.initials: O
authors.lastname: Bilsel
mesh_terms: D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology*; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D011489:Protein Denaturation; D017510:Protein Folding; D020673:Protein Renaturation; D017433:Protein Structure, Secondary; D053838:Scattering, Small Angle; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D013762:Tetrahydrofolate Dehydrogenase