title: Optimizing refolding and recovery of active recombinant Bacillus halodurans xylanase in polymer-salt aqueous two-phase system using surface response analysis.
abstract: An experimental design was used to determine optimal conditions for refolding of a recombinant thermostable and alkaline active xylanase from Bacillus halodurans in PEG-phosphate two-phase system. The influence of different experimental variables on the enzyme recovery has been evaluated. To build the mathematical model and minimize the number of experiments for the design parameters, response surface methodology with a face-centered central composite design (CCF) was defined based on the conditions found by preliminary tests that resulted in the highest refolding yield. The adequacy of the calculated model for the response was confirmed by means of variance analysis and additional experiments. Analysis of contours of constant response as a function of pH, polyethylene glycol (PEG) molecular weight and concentration, and salt concentration for different enzyme loads revealed different effects of these five factors on the studied parameters. Recovery of more than 92% active xylanase was predicted for a system with 18.3% (w/w) PEG 1000, 14.4% (w/w) phosphate at pH 8.5, and enzyme load corresponding to a protein concentration of about 0.05 mg/g system. The yield of the refolded enzyme was found to be optimal at 22 degrees C. The validity of the response model was verified by a good agreement between predicted and experimental results.
authors.affiliation: Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, SE-221 00 Lund, Sweden.
authors.forename: Farshad
authors.initials: F
authors.lastname: Rahimpour
authors.forename: Gashaw
authors.initials: G
authors.lastname: Mamo
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Feyzi
authors.forename: Saeid
authors.initials: S
authors.lastname: Maghsoudi
authors.forename: Rajni
authors.initials: R
authors.lastname: Hatti-Kaul
mesh_terms: D000704:Analysis of Variance; D001407:Bacillus / Q000201:enzymology*; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000378:metabolism*; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D008970:Molecular Weight; D010710:Phosphates / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000378:metabolism*; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012044:Regression Analysis
chemical_list: D010710:Phosphates; D011994:Recombinant Proteins; D011092:Polyethylene Glycols; D043364:Endo-1,4-beta Xylanases