Characterization of the Fast-Forming Intermediate, Des [30-75], in the Reductive Unfolding of Onconase

Guoqiang Xu, Mahesh Narayan, E. Welker, Harold A. Scheraga

Research output: Contribution to journalArticle

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Abstract

A fast-forming intermediate in the reductive unfolding of frog onconase (ONC), des [30-75], analogous to the des [40-95] intermediate found in the reductive unfolding of its structural homologue, bovine pancreatic ribonuclease A (RNase A), has been isolated and characterized. The midpoints of the thermal transition and chemical denaturing curves (representing global unfolding) indicate that the conformation of des [30-75] is considerably less stable than that of the parent molecule, suggesting that the (30-75) disulfide bond plays a significant role in the conformational stability of ONC. While des [30-75] is formed very quickly by a partial reduction of the parent molecule in a local unfolding step, it is not as easily susceptible to further reduction, indicating that its three disulfides are much more buried compared to the (30-75) disulfide bond in the parent protein. The nature of des [30-75] is similar to that of des [40-95] RNase A, in that des [30-75] ONC is also a disulfide-secure species. In addition, based on the resistance to mild reducing conditions, structured des species appear to form in ONC from unstructured three-disulfide-containing ensembles. This step is key in the oxidative folding of RNaseA, and is much faster in ONC than the formation of the structured des [40-95] species in RNase A.

Original languageEnglish
Pages (from-to)3246-3254
Number of pages9
JournalBiochemistry
Volume43
Issue number11
DOIs
Publication statusPublished - Mar 23 2004

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Pancreatic Ribonuclease
Disulfides
Molecules
Anura
Conformations
Hot Temperature
ranpirnase
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Characterization of the Fast-Forming Intermediate, Des [30-75], in the Reductive Unfolding of Onconase. / Xu, Guoqiang; Narayan, Mahesh; Welker, E.; Scheraga, Harold A.

In: Biochemistry, Vol. 43, No. 11, 23.03.2004, p. 3246-3254.

Research output: Contribution to journalArticle

Xu, Guoqiang ; Narayan, Mahesh ; Welker, E. ; Scheraga, Harold A. / Characterization of the Fast-Forming Intermediate, Des [30-75], in the Reductive Unfolding of Onconase. In: Biochemistry. 2004 ; Vol. 43, No. 11. pp. 3246-3254.
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