Oxidative folding and N-terminal cyclization of onconase

Details

Serval ID
serval:BIB_E0A78220B70A
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Oxidative folding and N-terminal cyclization of onconase
Journal
Biochemistry
Author(s)
Welker  E., Hathaway  L., Xu  G., Narayan  M., Pradeep  L., Shin  H. C., Scheraga  H. A.
ISSN
0006-2960 (Print)
Publication state
Published
Issued date
05/2007
Volume
46
Number
18
Pages
5485-93
Notes
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't --- Old month value: May 8
Abstract
Cyclization of the N-terminal glutamine residue to pyroglutamic acid in onconase, an anti-cancer chemotherapeutic agent, increases the activity and stability of the protein. Here, we examine the correlated effects of the folding/unfolding process and the formation of this N-terminal pyroglutamic acid. The results in this study indicate that cyclization of the N-terminal glutamine has no significant effect on the rate of either reductive unfolding or oxidative folding of the protein. Both the cyclized and uncyclized proteins seem to follow the same oxidative folding pathways; however, cyclization altered the relative flux of the protein in these two pathways by increasing the rate of formation of a kinetically trapped intermediate. Glutaminyl cyclase (QC) catalyzed the cyclization of the unfolded, reduced protein but had no effect on the disulfide-intact, uncyclized, folded protein. The structured intermediates of uncyclized onconase were also resistant to QC catalysis, consistent with their having a native-like fold. These observations suggest that, in vivo, cyclization takes place during the initial stages of oxidative folding, specifically, before the formation of structured intermediates. The competition between oxidative folding and QC-mediated cyclization suggests that QC-catalyzed cyclization of the N-terminal glutamine in onconase occurs in the endoplasmic reticulum, probably co-translationally.
Keywords
Animals Disulfides/chemistry Oxidation-Reduction Peptide Fragments/*chemistry/metabolism Peptides, Cyclic/*chemistry/metabolism *Protein Folding Pyrrolidonecarboxylic Acid/chemistry/metabolism Rana pipiens Ribonucleases/*chemistry/metabolism
Pubmed
Web of science
Create date
24/01/2008 14:40
Last modification date
20/08/2019 16:04
Usage data