title: Insights into the interactions between enzyme and co-solvents: stability and activity of stem bromelain.
abstract: In present study, an attempt is made to elucidate the effects of various naturally occurring osmolytes and denaturants on BM at pH 7.0. The effects of the varying concentrations of glycerol, sorbitol, sucrose, trehalose, urea and guanidinium chloride (GdnHCl) on structure, stability and activity of BM are explored by fluorescence spectroscopy, circular dichroism (CD), UV-vis spectroscopy and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Our experimental observations reveal that glycerol and sorbitol are acting as stabilizers at all concentrations while sucrose and trehalose are found to be destabilizers at lower concentrations, however, acted as stabilizers at higher concentrations. On the other hand, urea and GdnHCl are denaturants except at lower concentrations. There is a direct relationship between activity and conformational stability as the activity data are found to be in accordance with conformational stability parameters (ΔGu, Tm, ΔCp) and BM profile on SDS-PAGE.
authors.affiliation: Department of Chemistry, University of Delhi, Delhi 110 007, India.
authors.forename: Anjeeta
authors.initials: A
authors.lastname: Rani
authors.affiliation: Department of Chemistry, University of Delhi, Delhi 110 007, India. Electronic address: venkatesup@hotmail.com.
authors.forename: Pannuru
authors.initials: P
authors.lastname: Venkatesu
mesh_terms: D001963:Bromelains / Q000737:chemistry; D020134:Catalytic Domain; D002942:Circular Dichroism; D004789:Enzyme Activation; D004795:Enzyme Stability; D004798:Enzymes / Q000737:chemistry*; D011489:Protein Denaturation; D058767:Protein Unfolding; D012997:Solvents / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D004798:Enzymes; D012997:Solvents; D001963:Bromelains; C091760:stem bromelain
keywords: Activity; Biophysical techniques; Denaturants; Osmolytes; Stability