Université de Strasbourg, CNRS, Institut Charles Sadron (UPR22), 23 rue du Loess, 67034 Strasbourg Cedex 2, BP 84047, France.
Université de Strasbourg, Faculté de Chimie, UMR7140, 1 rue Blaise Pascal, 67008 Strasbourg Cedex, France.
Biomacromolecules. 2023 Aug 14;24(8):3794-3805. doi: 10.1021/acs.biomac.3c00445. Epub 2023 Aug 3.
Composite hydrogels composed of low-molecular-weight peptide self-assemblies and polysaccharides are gaining great interest as new types of biomaterials. Interactions between polysaccharides and peptide self-assemblies are well reported, but a molecular picture of their impact on the resulting material is still missing. Using the phosphorylated tripeptide precursor Fmoc-FFY (Fmoc, fluorenylmethyloxycarbonyl; F, phenylalanine; Y, tyrosine; , phosphate group), we investigated how hyaluronic acid (HA) influences the enzyme-assisted self-assembly of Fmoc-FFY generated in situ in the presence of alkaline phosphatase (AP). In the absence of HA, Fmoc-FFY peptides are known to self-assemble in nanometer thick and micrometer long fibers. The presence of HA leads to the spontaneous formation of bundles of several micrometers thickness. Using fluorescence recovery after photobleaching (FRAP), we find that in the bundles both () HA colocalizes with the peptide self-assemblies and () its presence in the bundles is highly dynamic. The attractive interaction between negatively charged peptide fibers and negatively charged HA chains is explained through molecular dynamic simulations that show the existence of hydrogen bonds. Whereas the Fmoc-FFY peptide self-assembly itself is not affected by the presence of HA, this polysaccharide organizes the peptide nanofibers in a nematic phase visible by small-angle X-ray scattering (SAXS). The mean distance between the nanofibers decreases by increasing the HA concentration , but remains always larger than the diameter of the peptide nanofibers, indicating that they do not interact directly with each other. At a high enough HA concentration, the nematic organization transforms into an ordered 2D hexagonal columnar phase with a nanofiber distance of 117 Å. Depletion interaction generated by the polysaccharides can explain the experimental power law variation and is responsible for the bundle formation and organization. Such behavior is thus suggested for the first time on nano-objects using polymers partially adsorbing on self-assembled peptide nanofibers.
由低分子量肽自组装体和多糖组成的复合水凝胶作为新型生物材料越来越受到关注。多糖与肽自组装体之间的相互作用已有很好的报道，但它们对所得材料的影响的分子图像仍然缺失。使用磷酸化三肽前体 Fmoc-FFY（Fmoc，芴甲氧羰基；F，苯丙氨酸；Y，酪氨酸； ，磷酸基团），我们研究了透明质酸（HA）如何影响碱性磷酸酶（AP）存在时原位生成的 Fmoc-FFY 的酶辅助自组装。在不存在 HA 的情况下，已知 Fmoc-FFY 肽自组装成纳米厚和微米长的纤维。HA 的存在导致几微米厚的束的自发形成。通过荧光恢复后光漂白（FRAP），我们发现，在束中（）HA 与肽自组装共定位，并且（）其在束中的存在是高度动态的。带负电荷的肽纤维与带负电荷的 HA 链之间的吸引力相互作用通过分子动力学模拟得到了解释，该模拟表明存在氢键。尽管 Fmoc-FFY 肽自组装本身不受 HA 的存在影响，但这种多糖以小角 X 射线散射（SAXS）可见的向列相组织肽纳米纤维。随着 HA 浓度的增加，纳米纤维之间的平均距离 减小，但始终大于肽纳米纤维的直径，表明它们彼此之间不直接相互作用。在足够高的 HA 浓度下，向列组织转变为有序的二维六方柱状相，纳米纤维距离 为 117 Å。多糖产生的耗散相互作用可以解释实验幂律变化 ，并负责束的形成和组织。这种行为因此首次在使用部分吸附在自组装肽纳米纤维上的聚合物的纳米物体上被提出。
