title: Structural characteristic of the initial unfolded state on refolding determines catalytic efficiency of the folded protein in presence of osmolytes.
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.
authors.affiliation: Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India.
authors.forename: Marina
authors.initials: M
authors.lastname: Warepam
authors.affiliation: Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India.
authors.forename: Gurumayum Suraj
authors.initials: GS
authors.lastname: Sharma
authors.affiliation: Department of Clinical Biochemistry, University of Kashmir, Srinagar, Jammu & Kashmir, India.
authors.forename: Tanveer Ali
authors.initials: TA
authors.lastname: Dar
authors.affiliation: School of Life Sciences, B.S. Abdur Rahman University, Chennai, India.
authors.forename: Md Khurshid Alam
authors.initials: MK
authors.lastname: Khan
authors.affiliation: Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, India.
authors.forename: Laishram Rajendrakumar
authors.initials: LR
authors.lastname: Singh
mesh_terms: D055162:Biocatalysis; D002942:Circular Dichroism; D019791:Guanidine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009994:Osmolar Concentration; D011489:Protein Denaturation; D058849:Protein Refolding; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature; D013816:Thermodynamics; D014508:Urea / Q000737:chemistry
chemical_list: D014508:Urea; D012259:Ribonuclease, Pancreatic; D019791:Guanidine