Folding kinetics of a fluorescent variant of monomeric lambda repressor.

Journal Article

A tryptophan-containing variant of monomeric lambda repressor has been made, and its folding kinetics were analyzed at 20 degreesC using fluorescence stopped-flow and dynamic NMR. Equilibrium denaturation curves obtained by circular dichroism, fluorescence, and NMR are superimposable. Stopped-flow analysis indicates that in the absence of denaturants the folding reaction is complete within the dead-time of the experiment. Within higher denaturant conditions, where the folding rate is slower, NMR and stopped-flow agree on the folding and unfolding rates of the protein. In 3.4 M urea and 1.8 M GdmCl, we show that the variant folds within 2 ms. Extrapolation indicates that the folding time is 20 micro(s) in the absence of denaturants. All folding and unfolding reactions displayed monoexponential kinetics, and no burst-phases were observed. In addition, the thermodynamic parameters Delta G and meq obtained from the kinetic analysis are consistent with the equilibrium experiments. The results support a two-state Dleft and right arrow N folding model.

Full Text

Duke Authors

Cited Authors

  • Ghaemmaghami, S; Word, JM; Burton, RE; Richardson, JS; Oas, TG

Published Date

  • June 23, 1998

Published In

Volume / Issue

  • 37 / 25

Start / End Page

  • 9179 - 9185

PubMed ID

  • 9636065

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi980356b

Language

  • eng

Conference Location

  • United States