KTH Royal Institute of Technology , Department of Fibre and Polymer Technology, Teknikringen 56, 100 44 Stockholm, Sweden.
Department of Science and Technology, University of Sannio , via dei Mulini 59/A, 82100 Benevento, Italy.
Biomacromolecules. 2017 Dec 11;18(12):4271-4280. doi: 10.1021/acs.biomac.7b01315. Epub 2017 Nov 27.
Peptides are often attached to polymer materials, as bioactive components, for the control of interactions between the material and its surrounding proteins and cells. However, synthesizing peptides and attaching them to polymers can be challenging and laborious. Herein, we describe the grafting of oligopeptides to an aliphatic polyester, using a one-step chemo-enzymatic synthesis with papain as the biocatalyst. To enable enzyme-mediated functionalization of the polyester, ethyl hept-6-enoylalaninate (grafter) was synthesized and attached to polylactide chains using thiol-ene click reactions. The oligopeptides were grafted onto the polylactide chains using two different synthetic routes: the grafting from strategy, in which the grafter was attached to the polyester prior to oligopeptide synthesis, or the grafting to strategy, in which oligopeptides were synthesized on the grafter first, then attached to the polymer chain. The final products were analyzed and their structures were confirmed using nuclear magnetic resonance (NMR). The peptide attachment was evaluated using size exclusion chromatography (SEC), contact angle measurement and energy-dispersive X-ray spectroscopy-scanning electron microscopy (EDS-SEM). Furthermore, the mechanistic aspects of the synthesis of the oligopeptides on the grafter were studied using molecular dynamics (MD) simulations. The simulation revealed that hydrogen bonding (between the P1 amide nitrogen of the grafter backbone and the carbonyl oxygen of D158 in the papain) maintain the grafter in a productive conformation to stabilize the transition state of nitrogen inversion, a key step of the biocatalytic mechanism. Apart from being biologically relevant, both experimental and computational results suggest that the designed grafter is a good template for initiating chemo-enzymatic synthesis. The results also showed that the grafting to strategy was more successful compared to the grafting from strategy. Overall, a successful synthesis of predefined peptide functionalized polylactide was prepared, where the oligopeptides were grafted in an easy, time efficient, and environmentally friendly way.
肽通常作为生物活性成分连接到聚合物材料上，以控制材料与其周围蛋白质和细胞的相互作用。然而，合成肽并将其连接到聚合物上可能具有挑战性和繁琐性。在此，我们描述了使用木瓜蛋白酶作为生物催化剂的一步化学-酶合成，将寡肽接枝到脂肪族聚酯上。为了使聚酯能够进行酶介导的功能化，合成了乙基庚-6-烯酰基丙氨酸（接枝剂），并通过硫醇-烯点击反应将其连接到聚乳酸链上。使用两种不同的合成路线将寡肽接枝到聚乳酸链上：接枝到策略，其中在合成寡肽之前将接枝剂连接到聚酯上；或者接枝到策略，其中首先在接枝剂上合成寡肽，然后将其连接到聚合物链上。使用核磁共振（NMR）分析和确认最终产物的结构。使用尺寸排阻色谱（SEC）、接触角测量和能量色散 X 射线光谱-扫描电子显微镜（EDS-SEM）评估肽的接枝。此外，使用分子动力学（MD）模拟研究了在接枝剂上合成寡肽的机制方面。模拟表明氢键（接枝剂主链上的 P1 酰胺氮和木瓜蛋白酶中 D158 的羰基氧之间）使接枝剂保持在生产性构象中，从而稳定氮反转的过渡态，这是生物催化机制的关键步骤。除了具有生物学相关性外，实验和计算结果均表明，所设计的接枝剂是引发化学-酶合成的良好模板。结果还表明，与接枝到策略相比，接枝到策略更成功。总体而言，成功地合成了具有预定肽功能化的聚乳酸，其中寡肽以简单、高效和环保的方式接枝。
