Rabiller-Baudry M, Bouguen A, Lucas D, Chaufer B
Laboratoire des Procédés de Séparation, UA Université de Rennes 1-INRA, France.
J Chromatogr B Biomed Sci Appl. 1998 Feb 27;706(1):23-32. doi: 10.1016/s0378-4347(97)00402-7.
The electrophoretic mobility of proteins was successfully determined by means of capillary electrophoresis (CE) with various background electrolytes (BGEs). The objective was focused on the variation in BGE physico-chemical composition and the consequential impact on the observed protein charge. Experimental and calculated mobilities, according to Henry's equation, versus ionic strength have been compared. For positively-charged lysozyme, a good agreement between observed and calculated mobilities was observed using triethanolamine chloride at pH 7.0 as the BGE. Mobility close to zero was shown using borate (pH 8.0) and phosphate (pH 7.0) at a low ionic strength of about 20 mmol l(-1), and as a consequence, specific adsorption of oxyanions was evidenced. Lysozyme retention in the case of reversed-phase high-performance liquid chromatography (RP-HPLC) was decreased by the presence of phosphate ions. CE and HPLC are complementary tools for characterizing the behaviour of lysozyme. On the other hand, the mobility of the negatively-charged alpha-lactalbumin remained constant as regards phosphate at pH 7.0 in the 20-200 mmol l(-1) range, contrary to the decrease that had been expected with the increasing ionic strength. beta-Lactoglobulin exhibited increasingly lower mobilities than those expected of boric acid/borate at pH 7.0 and 8.0 (I=20 mmol l(-1)).
通过毛细管电泳（CE）结合各种背景电解质（BGE）成功测定了蛋白质的电泳迁移率。研究重点在于BGE物理化学组成的变化及其对观察到的蛋白质电荷的相应影响。根据亨利方程，将实验测定的迁移率和计算得到的迁移率与离子强度进行了比较。对于带正电荷的溶菌酶，以pH 7.0的三乙醇胺氯化物作为BGE时，观察到的迁移率与计算得到的迁移率吻合良好。在约20 mmol l(-1)的低离子强度下，使用硼酸盐（pH 8.0）和磷酸盐（pH 7.0）时迁移率接近零，因此证明了氧阴离子的特异性吸附。在反相高效液相色谱（RP-HPLC）中，磷酸盐离子的存在降低了溶菌酶的保留率。CE和HPLC是表征溶菌酶行为的互补工具。另一方面，带负电荷的α-乳白蛋白在pH 7.0、20 - 200 mmol l(-1)范围内，相对于磷酸盐其迁移率保持恒定，这与预期的随离子强度增加而降低的情况相反。β-乳球蛋白在pH 7.0和8.0（I = 20 mmol l(-1)）时，其迁移率比硼酸/硼酸盐预期的迁移率越来越低。
