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Local events that affect specific regions of proteins are of utmost relevance for stability and function. The aim of this study is to quantitatively assess the importance of locally-focused dynamics by means of a simple chemical modification procedure. Taking human Frataxin as a working model, we investigated local fluctuations of the C-terminal region (the last 16 residues of the protein) by means of three L → C replacement mutants: L98C, L200C and L203C. The conformation and thermodynamic stability of each variant was assessed. All the variants exhibited native features and high stabilities: 9.1 (wild type), 8.1 (L198C), 7.0 (L200C) and 10.0 kcal mol −1 (L203C). In addition, kinetic rates of Cys chemical modification by DTNB and DTDPy were measured, conformational dynamics data were extracted and free energy for the local unfolding of the C-terminal region was estimated. The analysis of these results indicates that the conformation of the C-terminal region fluctuates with partial independence from global unfolding events. Additionally, numerical fittings of the kinetic model of the process suggest that the local transition occurs in the seconds to minutes timescale. In fact, standard free energy differences for local unfolding were found to be significantly lower than those of the global unfolding reaction, showing that chemical modification results may not be explained in terms of the global unfolding reaction alone. These results provide unequivocal experimental evidence of local phenomena with global effects and contribute to understanding how global and local stability are linked to protein dynamics. © 2019, The Author(s).


Documento: Artículo
Título:Global Implications of Local Unfolding Phenomena, Probed by Cysteine Reactivity in Human Frataxin
Autor:Faraj, S.E.; Noguera, M.E.; Delfino, J.M.; Santos, J.
Filiación:Alejandro Paladini Institute of Biological Chemistry and Chemical Physics (UBA-CONICET), Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, (C1113AAD), Buenos Aires, Argentina
Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencia Exactas y Naturales, Universidad de Buenos Aires. Instituto de Biociencias, Biotecnología y Biomedicina (iB3). Intendente Güiraldes 2160 - Ciudad Universitaria, C.A.B.A., 1428EGA, Argentina
Título revista:Scientific Reports
Título revista abreviado:Sci. Rep.


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---------- APA ----------
Faraj, S.E., Noguera, M.E., Delfino, J.M. & Santos, J. (2019) . Global Implications of Local Unfolding Phenomena, Probed by Cysteine Reactivity in Human Frataxin. Scientific Reports, 9(1).
---------- CHICAGO ----------
Faraj, S.E., Noguera, M.E., Delfino, J.M., Santos, J. "Global Implications of Local Unfolding Phenomena, Probed by Cysteine Reactivity in Human Frataxin" . Scientific Reports 9, no. 1 (2019).
---------- MLA ----------
Faraj, S.E., Noguera, M.E., Delfino, J.M., Santos, J. "Global Implications of Local Unfolding Phenomena, Probed by Cysteine Reactivity in Human Frataxin" . Scientific Reports, vol. 9, no. 1, 2019.
---------- VANCOUVER ----------
Faraj, S.E., Noguera, M.E., Delfino, J.M., Santos, J. Global Implications of Local Unfolding Phenomena, Probed by Cysteine Reactivity in Human Frataxin. Sci. Rep. 2019;9(1).