title: Lysozyme purification from tobacco extract by polyelectrolyte precipitation.
abstract: Tobacco is widely used as a model plant for feasibility studies of recombinant protein production from transgenic plants. However, dealing with large quantities of biomass to recover recombinant proteins is a challenge for down-stream processing. In this study, the effect of isoelectric precipitation on native tobacco protein was first studied. Among the three acids studied, hydrochloric acid is shown to be more effective than acetic or citric acid, and at pH 4, 60% of native tobacco protein was precipitated by HCl. Egg white lysozyme was used as the model protein to test the feasibility of polyelectrolyte precipitation in protein recovery from tobacco extract. Precipitation of lysozyme at pH 7 was shown ineffective probably because of the interference of polyphenolic acids. However, after isoelectric precipitation at pH 5 poly(acrylic) acid (PAA) was shown to precipitate 85% of the soluble lysozyme when the polymer dosage was increased to 1.5 mg polymer/mg lysozyme, while negligible amounts of native tobacco protein was co-precipitated. Lysozyme precipitation by PAA in tobacco extract obtained at pH 5 was also studied, and lysozyme yield was significant improved.
authors.affiliation: Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, 210 Seitz Hall, Blacksburg, VA 24061, USA. cmzhang@vt.edu
authors.forename: Chenming
authors.initials: C
authors.lastname: Zhang
authors.forename: Raymond
authors.initials: R
authors.lastname: Lillie
authors.forename: Jackie
authors.initials: J
authors.lastname: Cotter
authors.forename: David
authors.initials: D
authors.lastname: Vaughan
mesh_terms: D011232:Chemical Precipitation; D004573:Electrolytes / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D007525:Isoelectric Focusing; D009113:Muramidase / Q000302:isolation & purification*; D010936:Plant Extracts / Q000737:chemistry*; D014026:Nicotiana / Q000201:enzymology*
chemical_list: D004573:Electrolytes; D010936:Plant Extracts; D009113:Muramidase