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首页> 外文期刊>RSC Advances >Secondary structure of end group functionalized oligomeric-l-lysines: investigations of solvent and structure dependent helicity
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Secondary structure of end group functionalized oligomeric-l-lysines: investigations of solvent and structure dependent helicity

机译：端基官能化的低聚l-赖氨酸的二级结构：溶剂和结构依赖性螺旋度的研究

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Fibrillation of supramolecular building blocks represents an important model system for complex proteins and peptides, such as amyloidogenic proteins, displaying aggregation and subsequent collapse of their biological functions. In this work, we synthesized narrow-dispersed, end group-telechelic, oligomeric-( L -lysine(carboxybenzyl (Z)/trifluoroacetyl (TFA))) _( n ) s ( n = 3–33) as a model system for studying assembly and secondary structure formation, prepared via ring opening polymerization (ROP) of N -carboxyanhydrides (NCA). Our primary goal was to understand the influence of amino acid chain length and end group-modification on the secondary structure and fibrillation of the oligo-Z/TFA-protected lysines. Synthesis was accomplished by initiation of ROP with 11-amino-undecene, followed by complete chain end functionalization reactions of the N-terminus by 10-undecenoyl-chloride. The so obtained oligomeric-( L -lysine(Z/TFA)) _( n ) s were fractionated according to their number of repeating units ( n ) with preparative GPC using DMF as the eluent. As proven by MALDI-ToF MS, ~(1) H-NMR-spectroscopy and analytical GPC, they were separated into fractions with low polydispersity ( ? ) values, ranging from 1.02–1.08. Secondary structural investigations of these narrowly-dispersed oligomeric-( L -lysine(Z/TFA)) _( n ) s ( n = 33 ± 6, n = 18 ± 6, n = 12 ± 4, n = 5 ± 2) were accomplished by CD spectroscopy in TFE and HFIP, indicating that TFE was able to induce/stabilize the formation of α-helicity. Fibril formation of oligomeric-( L -lysine(Z/TFA)) _( n ) s with shorter chain lengths ( n = 7 and n = 3) were chosen to investigate the effect of the number of repeating units' role on the self-assembly of the oligomers in TFE. TEM images of these selected fractions, f19 with n = 7 and f28 with n = 3, showed that fibrillization occured and the formation of a dense fibrillar mesh was observed when the amino acid chain length is equal to 7. Therefore, the influences of the number of repeating units ( n ), end-group functionalities (mono- or bis-functional) and the choice of solvents (TFE or HFIP) on the propensity to form helical structure allowed us to calibrate their secondary structure.
机译：超分子构件的原纤化代表了复杂蛋白质和肽（例如淀粉样蛋白）的重要模型系统，显示出其生物功能的聚集和随后的崩溃。在这项工作中，我们合成了窄分散的端基端粒寡聚物-（L-赖氨酸（羧基苄基（Z）/三氟乙酰基（TFA）））_（n）s（n = 3–33）作为模型系统研究了通过N-羧基酐（NCA）的开环聚合（ROP）制备的组装和二级结构的形成。我们的主要目标是了解氨基酸链长度和端基修饰对寡聚Z / TFA保护的赖氨酸的二级结构和原纤化的影响。合成是通过用11-氨基十一碳烯引发ROP，然后通过10-十一碳烯酰氯完成N末端的链端官能化反应而完成的。将如此获得的寡聚-（L-赖氨酸（Z / TFA））_（n）s根据其重复单元数（n），使用DMF作为洗脱剂，通过制备型GPC进行分馏。 MALDI-ToF MS，〜（1）H-NMR光谱和分析型GPC证明，它们被分离成低多分散度（η）值在1.02-1.08之间的馏分。这些窄分散的低聚物-（L-赖氨酸（Z / TFA））_（n）s的二级结构研究（n = 33±6，n = 18±6，n = 12±4，n = 5±2）通过在TFE和HFIP中进行CD光谱分析可知，TFE能够诱导/稳定α-螺旋的形成。选择具有较短链长（n = 7和n = 3）的低聚-（L-赖氨酸（Z / TFA））_（n）s的原纤维形成，以研究重复单元数目对自我的影响-在TFE中组装低聚物。这些选定级分的f19（n = 7）和f28（n = 3）的TEM图像显示，当氨基酸链长等于7时，发生了原纤维化，并观察到致密的原纤维网状结构的形成。重复单元的数量（n），端基官能团（单官能或双官能）和溶剂（TFE或HFIP）形成螺旋结构的倾向性的选择使我们能够校准其二级结构。

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