Factors defining the effects of macromolecular crowding on dynamics and thermodynamic stability of heme proteins in-vitro,

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2018

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Elsevier

Abstract

The role of crowding agents on structure and activities of heme proteins has been established. Analysis of kinetic and thermodynamic parameters measured for CO-dissociation reaction of natively-folded carbonmonoxycytochrome c (NCO) and carbonmonoxymyoglobin (MbCO) at different [GdnHCl] or [Urea] in the presence of crowding agents (dextran 40, dextran 70 and ficoll 70) demonstrate that (i) at low denaturant concentrations, crowder presence enhances the denaturant-mediated restricted dynamics of NCO and MbCO, and (ii) at higher denaturant concentrations, large scale unfolding-fluctuations dominate the dynamics and inclusion of crowder counteracts the structural-fluctuations causing the unfolding of proteins. Thermodynamic analysis of thermal and urea-unfolding curves of cytochrome c (Cyt c) and myoglobin (Mb) measured at different [GdnHCl] in presence of crowding agents reveals that crowder presence counterbalances and strengthens the destabilizing action of GdnHCl on stability of Cyt c and Mb, respectively. This study further demonstrates that the size, shape and concentration of crowding agent modulate the effect of crowder on denaturant-mediated dynamics and thermodynamic stability of heme proteins.

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Keywords

Crowding agents, Constrained dynamics, Thermodynamic stability, Counteracting effect, Excluded volume effect

Citation

Kumar, Rajesh., Sharma, Deepak., Kumar, Vinay and et. al. (2018) Factors defining the effects of macromolecular crowding on dynamics and thermodynamic stability of heme proteins in-vitro. Archives of Biochemistry and Biophysics. Vol. 654, PP. 146-162. https://doi.org/10.1016/j.abb.2018.07.018

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