Study on Complexation of Proteins with Polyelectrolytes

蛋白质与聚电解质络合的研究

基本信息

批准号：
05044077
负责人：
KOKUFUTA Etsuo
金额：
$ 2.56万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

The complexation of proteins with natural and synthetic polyelectrolytes in an aqueous system in interesting from two points of view. The first concerns the way in which the polymers interact with non-flexible protein molecules, an understanding of which could provide a better explanation of the mechanisms of macromolecular interaction available in nature. The second concerns the extent to which biochemical activity is maintained in the resulting complexes, the answer to which is central to the molecular design of composite protein-polymer systems, such as immobilized enzymes, as well as the design of protein separation processes using water-soluble polymers.The present study has dealt with the formation of protein-polyelectrolyte complexes (PPCs) under different conditions of pH and salt concentration. Turbidimetric titration, quasi-elastic light scattering (QELS), static light scattering (SLS), electrophoretic light scattering (ELS) and fluorescence spectroscopy have been employed. I … More n addition, biochemical methods such as the measurement of enzymatic activity have also been employed in the appropriate cases. The main conclusions derived from these previous studies may be summarized as follows : (i) PPCs are formed mainly through electrostatic forces ; (ii) in salt-free systems, at least, protein molecules are complexed with flexible polyelectrolytes through 1 : 1 stoichiometric formation of ion pairs (or salt linkages) between oppositely charged groups ; (iii) the ion pairs between the polyelectrolyte and protein molecules are very weak, some of these bindings severed by changes in pH and the addition of small ions and polyions ; and (iv) there is an appreciable retention of biochemical function in theresultant complexes ; therefore, changes in the three-dimensional conformations of the protein molecules caused by complexation are not so large as to cause a loss of original functions.From the above results the processes of PPC formation may be inferred as follows : At first, many protein molecules are bound to one polyion to form an intrapolymer complex ; especially in salt-free systems, all of its polyion charges are stoichiometrically neutralized by the opposite charges of the proteins. After this, the resultant intrapolymer complexes interact with one another, yielding aggregates or coacervates. It appears likely that such an intrapolymer PPC consists of a number of protein molecules bridged or bundled together by one extended polyelectrolyte ion. The salt linkages maintaining the structure of the intrapolymer PPC seem to be very loose, because changes in pH or additions of other polyions sever some of the salt linkages. This looseness may make it possible for the protein and polyion molecules to undergo stoichiometric neutralization with oppositely charged groups through thermal motion. Less

从两个角度来看，在水性系统中，蛋白质与自然和合成的聚电解质的络合。第一个涉及聚合物与非芬芳蛋白质分子相互作用的方式，这种理解可以更好地解释自然界可用的大分子相互作用的机理。第二个问题涉及在产生的复合物中维持生化活性的程度，其答案对于复合蛋白质聚合物系统的分子设计至关重要，例如固定的酶，以及使用水溶性聚合物的蛋白质分离过程的设计。本研究与蛋白质的perlosition perlotiention complite and pholtery of Perylect of Perelectemect and pere persect of Perelecte precter（Perect）相比（Perelect）。已经采用了浊度滴定，准弹性光散射（QELS），静态光散射（SLS），电泳光散射（EL）和荧光光谱。在适当的情况下，还采用了更多的n添加生化方法，例如酶活性的测量。从这些先前的研究得出的主要结论可以总结如下：（i）PPC主要通过静电力形成；（ii）至少在无盐系统中，蛋白质分子与柔性聚电解质与相对电荷组之间的离子对（或盐连接）的1：1化学计量形成进行复合；（iii）聚电解质和蛋白质分子之间的离子对非常弱，其中一些结合因pH的变化而切断，而添加小离子和聚子；（iv）在造型络合物中，生化功能有明显的保留；因此，由络合物引起的蛋白质分子的三维构象的变化并不大于导致原始功能的损失。从上述结果可以推断出PPC形成的过程如下：首先，许多蛋白质分子与一个polyion结合到一个polyion以形成interpolymermermermermermermermermermermermermermermermermermermermermermermermermers络合物；尤其是在无盐系统中，其所有Polyour电荷都被蛋白质相反的电荷化石化。之后，所得的内聚合物复合物相互相互作用，产生聚集体或塞孔。这种内聚合物PPC似乎是由许多蛋白质分子组成的，由一个扩展的聚电解质离子桥接或捆绑在一起。维持内聚合物PPC结构的盐连接似乎很松散，因为pH值的变化或其他物质因素的添加切断了一些盐连接。这种松动可能使蛋白质和波利离子分子通过热运动通过带电的组进行化学计量中和。较少的