École Polytechnique Fédérale de Lausanne (EPFL), Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, Lausanne, Switzerland.
Biomacromolecules. 2012 Apr 9;13(4):1161-71. doi: 10.1021/bm300103u. Epub 2012 Mar 20.
Polymer-protein conjugates generated from side chain functional synthetic polymers are attractive because they can be easily further modified with, for example, labeling groups or targeting ligands. The residue specific modification of proteins with side chain functional synthetic polymers using the traditional coupling strategies may be compromised due to the nonorthogonality of the side-chain and chain-end functional groups of the synthetic polymer, which may lead to side reactions. This study explores the feasibility of the squaric acid diethyl ester mediated coupling as an amine selective, hydroxyl tolerant, and hydrolysis insensitive route for the preparation of side-chain functional, hydroxyl-containing, polymer-protein conjugates. The hydroxyl side chain functional polymers selected for this study are a library of amine end-functional, linear, midfunctional, hyperbranched, and linear-block-hyperbranched polyglycerol (PG) copolymers. These synthetic polymers have been used to prepare a diverse library of BSA and lysozyme polymer conjugates. In addition to exploring the scope and limitations of the squaric acid diethylester-mediated coupling strategy, the use of the library of polyglycerol copolymers also allows to systematically study the influence of molecular weight and architecture of the synthetic polymer on the biological activity of the protein. Comparison of the activity of PG-lysozyme conjugates generated from relatively low molecular weight PG copolymers did not reveal any obvious structure-activity relationships. Evaluation of the activity of conjugates composed of PG copolymers with molecular weights of 10000 or 20000 g/mol, however, indicated significantly higher activities of conjugates prepared from midfunctional synthetic polymers as compared to linear polymers of similar molecular weight.
由侧链功能合成聚合物生成的聚合物-蛋白质缀合物很有吸引力，因为它们可以很容易地进一步修饰，例如标记基团或靶向配体。由于合成聚合物的侧链和链末端官能团的非正交性，使用传统偶联策略对蛋白质进行残基特异性修饰可能会受到影响，这可能导致副反应。本研究探讨了使用丁二酸二乙酯作为胺选择性、羟基耐受性和水解不敏感的方法来制备侧链功能化、含羟基的聚合物-蛋白质缀合物的可行性。本研究选择的具有羟基侧链功能的聚合物是一系列胺端功能化的、线性的、中功能化的、超支化的和线性-支化超支化的聚甘油（PG）共聚物。这些合成聚合物已被用于制备各种牛血清白蛋白（BSA）和溶菌酶聚合物缀合物。除了探索丁二酸二乙酯介导的偶联策略的范围和局限性外，使用聚甘油共聚物库还可以系统地研究合成聚合物的分子量和结构对蛋白质生物活性的影响。比较相对低分子量 PG 共聚物生成的 PG-溶菌酶缀合物的活性并没有显示出任何明显的结构-活性关系。然而，对分子量为 10000 或 20000 g/mol 的 PG 共聚物组成的缀合物的活性评估表明，与具有相似分子量的线性聚合物相比，中功能化合成聚合物制备的缀合物的活性显著更高。
