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Unfolding Activity (unfolding + activity)
Selected AbstractsThe Membrane-Bound Lon Protease from Thermoplasma Displays Unfolding ActivityISRAEL JOURNAL OF CHEMISTRY, Issue 2 2006Henrike Besche The membrane-bound Lon protease from Thermoplasma acidophilum (Ta Lon) was shown to unfold and degrade a fusion of the green fluorescent protein with calmodulin (GFP,CaM). Unfolding and degradation were ATP-dependent reactions and could be inhibited by calcium ions, which are known to stabilize calmodulin. Notably, an inverse fusion of the same proteins, i.e., CaM,GFP, as well as GFP or GFP-SsrA, was neither unfolded nor degraded. Thus, Ta Lon seems to unfold and degrade preferentially protein substrates with an extended unstructured C-terminus. A set of Ta Lon variants mutated in critical residues of the AAA+ domain, were tested for their respective ATPase and GFP,CaM unfolding activity. This analysis revealed that the rate of ATP hydrolysis correlated with the efficiency of the GFP,CaM unfolding activity. In summary, we show here that the membrane-bound Ta Lon protease displays an unfolding activity, which is correlated with the rate of ATP hydrolysis. [source] A modified Ising model for the thermodynamic properties of local and global protein folding,unfolding observed by circular dichroism and small-angle X-ray scatteringJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Ying-Jen Shiu Based on the mean-field approximation, we have applied a modified Ising model to describe general protein unfolding behavior at thermodynamic equilibrium with the free energy contributed by the subgroup units (amino acids or peptide bonds) of the protein. With the thermodynamic properties of the protein, this model can associate the stepwise change of an unfolding fraction ratio profile with the local and global conformation unfolding. Taking cytochrome c (cyt c) as a model protein, we have observed, using small-angle X-ray scattering and circular dichroism (CD), the global and local structure changes for the protein in three kinds of denaturant environments: acid, urea and guanidine hydrochloride. The small-angle X-ray scattering and CD results are mapped to the unfolding fractions as a function of the pH value or denaturant concentration, from which we have extracted local and global unfolding free energies of cyt c in different denaturant environments using a modified Ising model. Based on the characteristics of the thermodynamic properties deduced from the local and global protein folding,unfolding, we discuss the thermodynamic stabilities of the protein in the three denaturant environments, and the possible correlation between the global conformation change of the protein and the local unfolding activities of the S,Fe bond in the Met80-heme and the ,-helices. [source] The Membrane-Bound Lon Protease from Thermoplasma Displays Unfolding ActivityISRAEL JOURNAL OF CHEMISTRY, Issue 2 2006Henrike Besche The membrane-bound Lon protease from Thermoplasma acidophilum (Ta Lon) was shown to unfold and degrade a fusion of the green fluorescent protein with calmodulin (GFP,CaM). Unfolding and degradation were ATP-dependent reactions and could be inhibited by calcium ions, which are known to stabilize calmodulin. Notably, an inverse fusion of the same proteins, i.e., CaM,GFP, as well as GFP or GFP-SsrA, was neither unfolded nor degraded. Thus, Ta Lon seems to unfold and degrade preferentially protein substrates with an extended unstructured C-terminus. A set of Ta Lon variants mutated in critical residues of the AAA+ domain, were tested for their respective ATPase and GFP,CaM unfolding activity. This analysis revealed that the rate of ATP hydrolysis correlated with the efficiency of the GFP,CaM unfolding activity. In summary, we show here that the membrane-bound Ta Lon protease displays an unfolding activity, which is correlated with the rate of ATP hydrolysis. [source] | ||||||||||