title: Effect of the pretreatment of lipase with organic solvents on its conformation and activity in reverse micelles.
abstract: The activity and conformation of Chromobacterium viscosum lipase-pretreated with various organic solvents were investigated. The pretreatment of lipase led to a substantial increase of enzyme activity in AOT (sodium bis [2-ethyl -1-hexyl] sulfosuccinate)/isooctane/water reverse micelles. Among the organic solvents used, n-hexane was found to be most effective. It was observed that higher hexane content with shorter agitation time and vice versa had almost the same effect on the initial activity of lipase. The kinetic study showed that the Michaelis constant (K m) and the substrate adsorption equilibrium constant (K ad) were reduced by the pretreatment of lipase with hexane, whereas the change in the maximum reaction rate (V max) was insignificant. The two spectroscopic techniques (Fluorescence spectra of lipase encapsulated in RMs and Fourier transform infrared [FTIR] spectra of lipase powders) were performed to detect possible conformational changes in the enzyme caused by the pretreatment. A correlation between the maximum fluorescence intensity and the activity of treated lipase was found as a function of agitation time. The FTIR spectrum of lipase showed a new shape peak corresponding to 1,500 cm-1 as a result of pretreatment with organic solvents.
authors.affiliation: Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma machi, Kanazawa, 920-1192, Japan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Moniruzzaman
authors.forename: Mahabubur Rahman
authors.initials: MR
authors.lastname: Talukder
authors.forename: Yoshishige
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Takuya
authors.initials: T
authors.lastname: Kawanishi
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis / Q000187:drug effects; D007700:Kinetics; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism*; D008823:Micelles; D011487:Protein Conformation / Q000187:drug effects; D012997:Solvents / Q000737:chemistry / Q000494:pharmacology*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D001426:Bacterial Proteins; D008823:Micelles; D012997:Solvents; D008049:Lipase; C454481:lipase, Chromobacterium viscosum