Polypeptide-Based Organogelators: Effects of Secondary Structure
Polypeptide-Based Organogelators: Effects of Secondary Structure
复制标题
DOI：
10.1021/ma201232a
复制
发表时间：
2011-09-27
期刊：
影响因子：
5.5
通讯作者：
Schlaad, Helmut
中科院分区：
文献类型：
--
作者：
Hermes, Florian;Otte, Katharina;Schlaad, Helmut
包含合成聚合物和多肽嵌段链段的生物启发嵌段共聚物，也称为多肽杂合共聚物、生物缀合物或“大分子嵌合体”，1已经成为聚合物科学的焦点超过四十年。2多肽嵌段聚合物可通过使用氨基官能化大分子引发剂的氨基酸N-羧基氰基丙烯酸酯（NCA，Leuchs'anhydride）3的开环聚合容易地获得，如Gallot及其同事所开创的。4，5后来德明和其他人开发了更复杂和有效的NCA聚合方法，使得能够以更大量合成明确定义的多肽和多肽杂合共聚物。6，7此外，自动化固相支持肽合成（SPPS）8已成为一种成熟且稳健的合成工具，用于制备具有单分散、单体序列限定的肽段的肽聚合物缀合物。9月12日到目前为止，生物缀合物中肽的氨基酸序列已经被大量改变，以研究亲水/疏水模式以及官能团的顺序和类型对相互作用能力或折叠成二级或四级结构的倾向的影响。虽然二级结构对自组装现象的重要性经常被强调，但将二级结构效应与决定此类极性嵌段共聚物体系中自组装的其他驱动力分离仍然很困难。只有很少的尝试已作出直接评估这些影响。然而，这将是有趣的理解软物质组装过程，例如有机或水凝胶化。在不改变氨基酸序列的情况下改变生物缀合物内肽段的立体异构体可能使得二级结构效应与化学组成脱钩，从而提供对自组装过程的洞察。最初的重要贡献，在这一领域作出了德明和同事。14 ± 16通过使D-和L-亮氨酸-NCA的混合物共聚合，对聚（L-赖氨酸）180（下标表示重复单元的平均数）进行嵌段延伸，产生聚（L-赖氨酸）180-嵌段-聚（DL-亮氨酸）40，在聚亮氨酸嵌段中具有统计立体序列。流变学显示，如果将该聚合物与同立体异构化合物聚（L-赖氨酸）180-嵌段-聚-（L-亮氨酸）40相比，则临界凝胶化浓度显著增加，凝胶强度显著降低。
Bioinspired block copolymers comprising synthetic polymer and polypeptide block segments, also referred to as polypeptide hybrid copolymers, bioconjugates, or “macromolecular chimeras”, 1 have been in the focus of polymer science for now more than four decades. 2 Polypeptide block polymers are readily available through ring-opening polymerization of amino acid N-carboxyanhydrides (NCA, Leuchs’ anhydrides) 3 using amino-functionalized macroinitiators, as pioneered by Gallot and co-workers. 4, 5 More sophisticated and effective methods of NCA polymerization have later been developed by Deming and others, enabling the synthesis of well-defined polypeptides and polypeptide hybrid copolymers in larger amounts. 6, 7 Besides, automated solid-phase supported peptide synthesis (SPPS) 8 has emerged as an established and robust synthesis tool to make peptideÀpolymer conjugates with monodisperse, monomer sequence-defined peptide segments. 9À12So far, amino acid sequences of peptides in bioconjugates have been intensively altered to study the impact of hydrophilic/hydrophobic pattern as well as the order and type of functional groups on interaction capabilities or propensities to fold into secondary or quaternary structures. 13 Although the importance of secondary structure on self-assembly phenomena was often highlighted, the separation of secondary structure effects from other driving forces that determine self-assembly in such polar block copolymer systems remains difficult. Only few attempts have been made to directly evaluate these effects. This, however, would be interesting for understanding soft matter assembly processes, for instance organo-or hydrogelation. Altering the stereoisomers of peptide segments within bioconjugates without changing the amino acid sequence might enable the decoupling of secondary structure effects from chemical composition and hence provides insight into self-assembly processes. Initial important contributions in this field were made by Deming and co-workers. 14À16 Block extension of a poly-(L-lysine) 180 (the subscript denoting the average number of repeat units) by copolymerization a mixture of D-and L-leucine-NCAs yielded a poly (L-lysine) 180-block-poly (DL-leucine) 40 with a statistic stereosequence in the polyleucine block. Rheology revealed a significantly increased critical gelation concentration and strongly reduced gel strength if this polymer was compared to the homo stereoisomeric compound poly (L-lysine) 180-block-poly-(L-leucine) 40.