Dv. Laurents et al., CHARACTERIZATION OF A RIBONUCLEASE-S REFOLDING INTERMEDIATE, Philosophical transactions-Royal Society of London. Physical sciences and engineering, 345(1674), 1993, pp. 131-140
During ribonuclease S (RNase S) refolding, two peptide fragments recog
nize each other, and bind together to form a refolding intermediate wh
ich slowly converts to the native state. We have characterized this re
folding intermediate using absorbance, circular dichroism (CD), and nu
clear magnetic resonance (NMR) spectroscopies. These techniques reveal
significant amounts of both secondary and tertiary structure; the int
ermediate differs from a molten globule in being packed and native-lik
e, but it resembles a molten globule in having no near-ultraviolet (UV
) CD spectrum. Final refolding is slow and accompanies proline isomeri
zation. The results show that at least two separate stages are observe
d in the formation of the tertiary structure of RNaseS.