Structural characteristic of the initial unfolded state on refolding determines catalytic efficiency of the folded protein in presence of osmolytes

PLoS One. 2014 Oct 14;9(10):e109408. doi: 10.1371/journal.pone.0109408. eCollection 2014.

Abstract

Osmolytes are low molecular weight organic molecules accumulated by organisms to assist proper protein folding, and to provide protection to the structural integrity of proteins under denaturing stress conditions. It is known that osmolyte-induced protein folding is brought by unfavorable interaction of osmolytes with the denatured/unfolded states. The interaction of osmolyte with the native state does not significantly contribute to the osmolyte-induced protein folding. We have therefore investigated if different denatured states of a protein (generated by different denaturing agents) interact differently with the osmolytes to induce protein folding. We observed that osmolyte-assisted refolding of protein obtained from heat-induced denatured state produces native molecules with higher enzyme activity than those initiated from GdmCl- or urea-induced denatured state indicating that the structural property of the initial denatured state during refolding by osmolytes determines the catalytic efficiency of the folded protein molecule. These conclusions have been reached from the systematic measurements of enzymatic kinetic parameters (Km and kcat), thermodynamic stability (Tm and ΔHm) and secondary and tertiary structures of the folded native proteins obtained from refolding of various denatured states (due to heat-, urea- and GdmCl-induced denaturation) of RNase-A in the presence of various osmolytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biocatalysis
  • Circular Dichroism
  • Guanidine / chemistry
  • Hydrogen-Ion Concentration
  • Kinetics
  • Osmolar Concentration
  • Protein Denaturation
  • Protein Refolding
  • Ribonuclease, Pancreatic / chemistry*
  • Ribonuclease, Pancreatic / metabolism
  • Temperature
  • Thermodynamics
  • Urea / chemistry

Substances

  • Urea
  • Ribonuclease, Pancreatic
  • Guanidine

Grants and funding

This work was supported by the grants from the Department of Science and Technology (grant no: SR/SO/BB-0003/2011) and Council of Scientific and Industrial Research (CSIR) (grant no: 37(1597)/13/EMR-II). LRS and MW also acknowledge CSIR for the financial assistance provided to MW in the form of research fellowship (File. no. 09/045(0992)/2010-EMR-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.