Reference : Tem-1 Beta-Lactamase Folds in a Nonhierarchical Manner with Transient Non-Native Inte...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
http://hdl.handle.net/2268/16639
Tem-1 Beta-Lactamase Folds in a Nonhierarchical Manner with Transient Non-Native Interactions Involving the C-Terminal Region
English
Lejeune, Annabelle [Université de Liège - ULg > Département des sciences de la vie > GIGA-R : Biologie et génétique moléculaire >]
Pain, R. H. [> > > >]
Charlier, Paulette mailto [Université de Liège - ULg > > Centre d'ingénierie des protéines >]
Frère, Jean-Marie mailto [Université de Liège - ULg > Département des sciences de la vie > Département des sciences de la vie >]
Matagne, André mailto [Université de Liège - ULg > Département des sciences de la vie > Enzymologie >]
29-Jan-2008
Biochemistry
47
4
1186-93
Yes (verified by ORBi)
International
0006-2960
[en] enzyme kinetics ; beta-lactamase ; molecular modelling ; protein stability ; therml unfolding
[en] The conformational stability and kinetics of refolding and unfolding of the W290F mutant of TEM-1 beta-lactamase have been determined as a function of guanidinium chloride concentration. The activity and spectroscopic properties of the mutant enzyme did not differ significantly from those of the wild type, indicating that the mutation has only a very limited effect on the structure of the protein. The stability of the folded protein is reduced, however, by 5-10 kJ mol-1 relative to that of the molten globule intermediate (H), but the values of the folding rate constants are unchanged, suggesting that Trp-290 becomes organized in its nativelike environment only after the rate-limiting step; i.e., the C-terminal region of the enzyme folds very late. In contrast to the significant increase in fluorescence intensity seen in the dead time (3-4 ms) of refolding of the wild-type protein, no corresponding burst phase was observed with the mutant enzyme, enabling the burst phase to be attributed specifically to the C-terminal Trp-290. This residue is suggested to be buried in a nonpolar environment from which it has to escape during subsequent folding steps. With both proteins, fast early collapse leads to a folding intermediate in which the C-terminal region of the polypeptide chain is trapped in a non-native structure, consistent with a nonhierarchical folding process.
http://hdl.handle.net/2268/16639

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