title: Effect of organic solvents on the molten globule state of procerain: beta-sheet to alpha-helix switchover in presence of trifluoroethanol.
abstract: The effect of methanol and trifluoroethanol (TFE) on the structure and folding of molten globule state of procerain, a cysteine protease from Calotropis procera, was studied by circular dichroism spectroscopy. The magnitude of ellipticity at 215 nm, as a measure of beta-sheet content, is dependent on the concentration of the TFE. Interestingly, a switch over from the beta-sheet structure of the molten globule state to alpha-helix was observed at 60% TFE and the ellipticity at 222 nm increased as a function of TFE concentration beyond this critical TFE concentration. Temperature induced unfolding of the molten globule state of procerain in 10% methanol showed stabilization of alpha-rich domain with concomitant destabilization of beta-rich domain. Using higher concentration of methanol (20-40 %) had no stabilizing effect on the alpha-rich domain however, the beta-rich domain was destabilized, indicating that the stability of the domains were not interdependent and that a low concentration of methanol induced stabilization in alpha-rich domain.
authors.affiliation: Molecular Biology Unit, Institute of Medicinal Sciences, Banaras Hindu University, Varanasi-221 005, India.
authors.forename: Vikash Kumar
authors.initials: VK
authors.lastname: Dubey
authors.forename: Ashu
authors.initials: A
authors.lastname: Shah
authors.forename: Medicherla Venkata
authors.initials: MV
authors.lastname: Jagannadham
authors.forename: Arvind Mohan
authors.initials: AM
authors.lastname: Kayastha
mesh_terms: D031107:Calotropis; D002942:Circular Dichroism; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D006358:Hot Temperature; D011489:Protein Denaturation / Q000187:drug effects; D017433:Protein Structure, Secondary / Q000187:drug effects; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics; D014270:Trifluoroethanol / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D012997:Solvents; D014270:Trifluoroethanol; D003546:Cysteine Endopeptidases; C474045:procerain