Ultrarapid mixing experiments reveal that Im7 folds via an on-pathway intermediate

Andrew P. Capaldi, M. C.Ramachandra Shastry, Colin Kleanthous, Heinrich Roder, Sheena E. Radford

Research output: Contribution to journalArticlepeer-review

155 Scopus citations


Many proteins populate partially organized structures during folding. Since these intermediates often accumulate within the dead time (2-5 ms) of conventional stopped-flow and quench-flow devices, it has been difficult to determine their role in the formation of the native state. Here we use a microcapillary mixing apparatus, with a time resolution of ∼150 μs, to directly follow the formation of an intermediate in the folding of a four-helix protein, Im7. Quantitative kinetic modeling of folding and unfolding data acquired over a wide range of urea concentrations demonstrate that this intermediate ensemble lies on a direct path from the unfolded to the native state.

Original languageEnglish (US)
Pages (from-to)68-72
Number of pages5
JournalNature Structural Biology
Issue number1
StatePublished - 2001

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Genetics


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