title: Protein Selectivity Controlled by Polymer Charge Density and Protein Yield: Carboxylated Polysaccharides versus Sulfated Polysaccharides.
abstract: The effect of polymer charge density on protein selectivity in the presence of carboxylated polysaccharides (CPS) and sulfated polysaccharides (SPS) was investigated for Kunitz trypsin inhibitor/Bowman-Birk protease inhibitor (KTI/BBI, KBM). To determine the conditions for coacervation or precipitation as a function of polymer charge densities, turbidimetric titrations and Tricine-SDS-PAGE were used. Polymer charge density as well as chain flexibility greatly influenced the strength of interactions and protein recovery. Although charge compensation must occur for CPS-KBM complexes, SPS-KBM systems did not require conservation of charge neutrality. Despite their similar isoelectric points, KTI bound preferentially to CPS and SPS due to its higher affinity compared to BBI. Complexation of KBM with the polysaccharide with the lowest charge density, arabic gum, expectedly cannot realize the purification of BBI under conditions where binding to more highly charged polysaccharides occurs. This work will be beneficial to selective purification of target proteins through control of protein-polysaccharide complexation.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University , 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China.
authors.forename: Xingfei
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University , 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Hua
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University , 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China.
authors.forename: Yeming
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University , 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China.
authors.forename: Xiangzhen
authors.initials: X
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University , 1800 Lihu Avenue, Wuxi, Jiangsu Province 214122, People's Republic of China.
authors.forename: Caimeng
authors.initials: C
authors.lastname: Zhang
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D010940:Plant Proteins / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D013025:Glycine max / Q000737:chemistry; D014358:Trypsin Inhibitor, Bowman-Birk Soybean / Q000737:chemistry; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000737:chemistry
chemical_list: D010940:Plant Proteins; D011108:Polymers; D011134:Polysaccharides; D014358:Trypsin Inhibitor, Bowman-Birk Soybean; D014360:Trypsin Inhibitor, Kunitz Soybean
keywords: BBI; KTI; carboxylated polysaccharides; charge density; charge neutrality; complexation; sulfated polysaccharides