Romanini Diana, Braia Mauricio, Angarten Rodrigo Giatte, Loh Watson, Picó Guillermo
Bioseparation Lab, Physical-Chemistry Department, Faculty of Biochemical and Pharmaceutical Sciences, National University of Rosario, FonCyT, CIUNR and CONICET, Suipacha 570, S2002RLK, Rosario, Argentina.
J Chromatogr B Analyt Technol Biomed Life Sci. 2007 Sep 15;857(1):25-31. doi: 10.1016/j.jchromb.2007.06.025. Epub 2007 Jun 30.
The complex formation between the basic protein lysozyme and anionic polyelectrolytes: poly acrylic acid and poly vinyl sulfonic acid was studied by turbidimetric and isothermal calorimetric titrations. The thermodynamic stability of the protein in the presence of these polymers was also studied by differential scanning calorimetry. The lysozyme-polymer complex was insoluble at pH lower than 6, with a stoichiometric ratio (polymer per protein mol) of 0.025-0.060 for lysozyme-poly vinyl sulfonic acid and around 0.003-0.001 for the lysozyme-poly acrylic acid. NaCl 0.1M inhibited the complex precipitation in agreement with the proposed coulombic mechanism of complex formation. Enthalpic and entropic changes associated to the complex formation showed highly negative values in accordance with a coulombic interaction mechanism. The protein tertiary structure and its thermodynamic stability were not affected by the presence of polyelectrolyte.
通过比浊滴定法和等温滴定量热法研究了碱性蛋白质溶菌酶与阴离子聚电解质（聚丙烯酸和聚乙烯磺酸）之间的复合物形成。还通过差示扫描量热法研究了在这些聚合物存在下蛋白质的热力学稳定性。溶菌酶 - 聚合物复合物在pH低于6时不溶，溶菌酶 - 聚乙烯磺酸的化学计量比（每摩尔蛋白质的聚合物）为0.025 - 0.060，溶菌酶 - 聚丙烯酸的化学计量比约为0.003 - 0.001。0.1M的NaCl抑制了复合物沉淀，这与所提出的复合物形成的库仑机制一致。与复合物形成相关的焓变和熵变显示出高度负值，这与库仑相互作用机制一致。聚电解质的存在不影响蛋白质的三级结构及其热力学稳定性。
