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Yeast hexokinase isoenzyme ScHxk2: stability of a two-domain protein with discontinuous domains

Item Type:Article
Title:Yeast hexokinase isoenzyme ScHxk2: stability of a two-domain protein with discontinuous domains
Creators Name:Lilie, H. and Baer, D. and Kettner, K. and Weininger, U. and Balbach, J. and Naumann, M. and Mueller, E.C. and Otto, A. and Gast, K. and Golbik, R. and Kriegel, T.
Abstract:The hexokinase isoenzyme 2 of Saccharomyces cerevisiae (ScHxk2) represents an archetype of a two-domain protein with the active site located in a cleft between the two domains. Binding of the substrate glucose results in a rigid body movement of the two domains leading to a cleft closure of the active site. Both domains of this enzyme are composed of discontinuous peptide sequences. This structural feature is reflected in the stability and folding of the ScHxk2 protein. Structural transitions induced by urea treatment resulted in the population of a thermodynamically stable folding intermediate, which, however, does not correspond to a molecule with one domain folded and the other unfolded. As demonstrated by different spectroscopic techniques, both domains are structurally affected by the partial denaturation. The intermediate possesses only 40% of the native secondary structural content and a substantial increase in the Stokes radius as judged by circular dichroism and dynamic light scattering analyses. One-dimensional ¹H NMR data prove that all tryptophan residues are in a non-native environment in the intermediate, indicating substantial changes in the tertiary structure. Still, the intermediate possesses quite a high stability for a transition intermediate of about DeltaG = -22 kJ mol(-1).
Keywords:Dynamic Light Scattering, NMR, ScHxk2, Stability, Transition Intermediate
Source:Protein Engineering Design and Selection
Publisher:Oxford University Press
Page Range:79-87
Date:January 2011
Official Publication:https://doi.org/10.1093/protein/gzq098
PubMed:View item in PubMed

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