Skoulas Dimitrios, Stavroulaki Dimitra, Santorinaios Konstantinos, Iatrou Hermis
Department of Chemistry, University of Athens, Panepistimiopolis, 15771 Zografou, Athens, Greece.
Polymers (Basel). 2017 Oct 30;9(11):564. doi: 10.3390/polym9110564.
The highly diverse and sophisticated action of proteins results from their equally diverse primary structure, which along with the nature of interactions between the amino acids, defines the higher self-assembly of proteins. The interactions between amino acids can be very complicated, and their understanding is necessary in order to elucidate the protein structure-properties relationship. A series of well-defined hybrid-polypeptidic diblock copolymers of the type m-PEO-b-poly(His-co-Gly) and m-PEO-b-poly(His-co-Ala) was synthesized through the ring opening polymerization of the -carboxyanhydrides of the corresponding amino acids, with a molar ratio of the hydrophobic peptide to histidine at 10%, 20% and 40%. The excellent purity of the monomers combined with the high vacuum techniques resulted in controlled polymerization with high molecular and compositional homogeneity. FT-IR, as well as circular dichroism, were employed to investigate the secondary structure of the polymers, while DLS, SLS and ζ-potential were utilized to study the aggregates formed in aqueous solutions, as well as their pH responsiveness. The results revealed that the randomly distributed monomeric units of glycine or alanine significantly influence L-histidine's structure. Depending on the pH, aggregates with a different structure, different molecular characteristics and a different surface charge are formed, potentially leading to very interesting bioapplications.
蛋白质高度多样且复杂的功能源于其同样多样的一级结构，一级结构连同氨基酸之间相互作用的性质，决定了蛋白质更高层次的自组装。氨基酸之间的相互作用可能非常复杂，为了阐明蛋白质结构与性质的关系，对其进行了解是必要的。通过相应氨基酸的α-羧基环酐的开环聚合反应，合成了一系列定义明确的杂化多肽二嵌段共聚物，即m-PEO-b-聚（组氨酸-共-甘氨酸）和m-PEO-b-聚（组氨酸-共-丙氨酸），疏水肽与组氨酸的摩尔比分别为10%、20%和40%。单体的高纯度与高真空技术相结合，实现了具有高分子量和组成均匀性的可控聚合。利用傅里叶变换红外光谱（FT-IR）以及圆二色性来研究聚合物的二级结构，同时利用动态光散射（DLS）、静态光散射（SLS）和ζ-电位来研究在水溶液中形成的聚集体及其pH响应性。结果表明，甘氨酸或丙氨酸的随机分布单体单元对L-组氨酸的结构有显著影响。根据pH值的不同，会形成具有不同结构、不同分子特征和不同表面电荷的聚集体，这可能会带来非常有趣的生物应用。
