The rapid kinetic phase that leads from unfolded species to transient folding intermediates in dihydrofolate reductase from Escherichia coli was examined by site-directed mutagenesis and by physicochemical means. The absence of this fluorescence-detected phase in the refolding of the Trp-74Phe mutant protein strongly implies that this early phase in refolding can be assigned to just one of the five Trp residues in the protein, Trp-74. In addition, water-soluble fluorescence quenching agents, iodide and cesium, have a much less significant effect on this early step in refolding than on the slower phases that lead to native and native-like conformers. These and other data imply that an important early event in the folding of dihydrofolate reductase is the formation of a hydrophobic cluster which protects Trp-74 from solvent. Study holds ProTherm entries: 10792, 10793 Extra Details: additive : 2-mercaptethanol(1 mM), protein folding; folding intermediates; hydrophobic effect;,tryptophan fluorescence; site-directed mutagenesis
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:40 p.m.
|Number of data points||3|
|Proteins||Dihydrofolate reductase ; Dihydrofolate reductase|
|Assays/Quantities/Protocols||Experimental Assay: ddG_H2O ; Experimental Assay: Cm|
|Libraries||Mutations for sequence MISLIAALAVDRVIGMENAMPWNLPADLAWFKRNTLDKPVIMGRHTWESIGRPLPGRKNIILSSQPGTDDRVTWVKSVDEAIAACGDVPEIMVIGGGRVYEQFLPKAQKLYLTHIDAEVEGDTHFPDYEPDDWESVFSEFHDADAQNSHSYCFEILERR|