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Analysis of the pH-dependent thermodynamic stability, local motions, and microsecond folding kinetics of carbonmonoxycytochrome c.
Arch Biochem Biophys. 2016 09 15; 606:16-25.AB

Abstract

This paper analyzes the effect of pH on thermodynamic stability, low-frequency local motions and microsecond folding kinetics of carbonmonoxycytochrome c (Cyt-CO) all across the alkaline pH-unfolding transition of protein. Thermodynamic analysis of urea-induced unfolding transitions of Cyt-CO measured between pH 6 and pH 11.9 reveals that Cyt-CO is maximally stable at pH∼9.5. Dilution of unfolded Cyt-CO into refolding medium forms a native-like compact state (NCO-state), where Fe(2+)-CO interaction persists. Kinetic and thermodynamic parameters measured for slow thermally-driven CO dissociation (NCO→N+CO) and association (N+CO→NCO) reactions between pH 6.5 and pH 13 reveal that the thermal-motions of M80-containing Ω-loop are decreased in subdenaturing limit of alkaline pH. Laser photolysis of Fe(2+)-CO bond in NCO-state triggers the microsecond folding (NCO→N). The microsecond kinetics measured all across the alkaline pH-unfolding transition of Cyt-CO produce rate rollover in the refolding limb of chevron plot, which suggests a glass transition of NCO en route to N. Between pH 7 and pH 11.9, the natural logarithm of the microsecond folding rate varies by < 1.5 units while the natural logarithm of apparent equilibrium constant varies by 11.8 units. This finding indicates that the pH-dependent ionic-interactions greatly affect the global stability of protein but have very small effect on folding kinetics.

Authors+Show Affiliations

Centre for Chemical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, 151001, India; School of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology University, Patiala, 147004, India. Electronic address: rajeshchem01@gmail.com.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

27424489

Citation

Kumar, Rajesh. "Analysis of the pH-dependent Thermodynamic Stability, Local Motions, and Microsecond Folding Kinetics of Carbonmonoxycytochrome C." Archives of Biochemistry and Biophysics, vol. 606, 2016, pp. 16-25.
Kumar R. Analysis of the pH-dependent thermodynamic stability, local motions, and microsecond folding kinetics of carbonmonoxycytochrome c. Arch Biochem Biophys. 2016;606:16-25.
Kumar, R. (2016). Analysis of the pH-dependent thermodynamic stability, local motions, and microsecond folding kinetics of carbonmonoxycytochrome c. Archives of Biochemistry and Biophysics, 606, 16-25. https://doi.org/10.1016/j.abb.2016.07.010
Kumar R. Analysis of the pH-dependent Thermodynamic Stability, Local Motions, and Microsecond Folding Kinetics of Carbonmonoxycytochrome C. Arch Biochem Biophys. 2016 09 15;606:16-25. PubMed PMID: 27424489.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Analysis of the pH-dependent thermodynamic stability, local motions, and microsecond folding kinetics of carbonmonoxycytochrome c. A1 - Kumar,Rajesh, Y1 - 2016/07/15/ PY - 2016/03/12/received PY - 2016/06/11/revised PY - 2016/07/13/accepted PY - 2016/7/19/entrez PY - 2016/7/19/pubmed PY - 2017/5/24/medline KW - Ionic interactions KW - Low-frequency local motion KW - Microsecond folding kinetics KW - Thermodynamic stability SP - 16 EP - 25 JF - Archives of biochemistry and biophysics JO - Arch Biochem Biophys VL - 606 N2 - This paper analyzes the effect of pH on thermodynamic stability, low-frequency local motions and microsecond folding kinetics of carbonmonoxycytochrome c (Cyt-CO) all across the alkaline pH-unfolding transition of protein. Thermodynamic analysis of urea-induced unfolding transitions of Cyt-CO measured between pH 6 and pH 11.9 reveals that Cyt-CO is maximally stable at pH∼9.5. Dilution of unfolded Cyt-CO into refolding medium forms a native-like compact state (NCO-state), where Fe(2+)-CO interaction persists. Kinetic and thermodynamic parameters measured for slow thermally-driven CO dissociation (NCO→N+CO) and association (N+CO→NCO) reactions between pH 6.5 and pH 13 reveal that the thermal-motions of M80-containing Ω-loop are decreased in subdenaturing limit of alkaline pH. Laser photolysis of Fe(2+)-CO bond in NCO-state triggers the microsecond folding (NCO→N). The microsecond kinetics measured all across the alkaline pH-unfolding transition of Cyt-CO produce rate rollover in the refolding limb of chevron plot, which suggests a glass transition of NCO en route to N. Between pH 7 and pH 11.9, the natural logarithm of the microsecond folding rate varies by < 1.5 units while the natural logarithm of apparent equilibrium constant varies by 11.8 units. This finding indicates that the pH-dependent ionic-interactions greatly affect the global stability of protein but have very small effect on folding kinetics. SN - 1096-0384 UR - https://www.unboundmedicine.com/medline/citation/27424489/Analysis_of_the_pH_dependent_thermodynamic_stability_local_motions_and_microsecond_folding_kinetics_of_carbonmonoxycytochrome_c_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0003-9861(16)30242-9 DB - PRIME DP - Unbound Medicine ER -