Preparation of Enzyme-Degradable Dendritic Macromolecules

以L-赖氨酸为起始原料制备的赖氨酸树枝状聚合物有望成为生物相容性和可生物降解的纳米材料，用于药物输送和基因治疗等生物医学应用。支化结构通常通过α-和ε-氨基与赖氨酸的羧基的偶联反应制备。由于ε-氨基在生物识别中起着重要作用，因此ε-氨基的存在降低了赖氨酸树枝状大分子的酶降解性。当注射到活体中时，降低的降解性可能导致赖氨酸树枝状聚合物的积累。该研究项目旨在生产用于生物医学应用的新型酶可降解树枝状聚合物。为了实现这一目标，制备了一系列保留每个赖氨酸的ε-氨基的赖氨酸树枝状聚合物。本文还对新型赖氨酸树枝状大分子的酶降解进行了研究，以评价ε-氨基对酶降解的影响。 ...更多信息 由甘氨酸和赖氨酸组成的树状大分子被设计为新型赖氨酸树状大分子的结构单元。肽低聚物通过酸敏感性三苯甲基树脂上的常规固相合成来制备。肽寡聚物的α-和ε-氨基分别由9-芴基甲氧羰基（Fmoc）和叔丁氧基羰基（BOC）基团保护。通过NMR和MALDI-TOF MS光谱测量确认肽低聚物的结构。以寡肽为结构单元，采用Fmoc固相合成策略，在Wang树脂上合成了赖氨酸树枝状大分子。通过三氟乙酸的最终切割导致形成脱保护的赖氨酸树枝状聚合物，其在每个构建单元上具有ε-氨基。通过制备型HPLC纯化的每一代和两代树枝状聚合物通过分析型HPLC显示出单峰。通过MALDI-TOF MS测量确认树枝状聚合物的分子量。还观察到，与用于常规肽合成的BOC基团脱保护的情况相比，BOC基团的裂解需要延长的反应时间。由于肽低聚物的大规模生产的困难，从肽低聚物制备高代树枝状聚合物和酶降解研究已经被推迟。虽然这项由Grand-in-Aid资助的科研项目已经结束，但该项目仍在继续进行，以创造新的酶可降解树枝状聚合物。少

Lysine Dendrimers prepared from L-lysine as a starting material are expected to be biocompatible and biodegradable nano materials for biomedical applications, such as drug delivery and gene therapy. The branching architecture is usually prepared by the coupling reaction of both α-and ε-amino groups with the carboxylic group of lysine. Since the ε-amino group plays important roles in biological recognition, the luck of ε-amino group reduces the degradability of the lysine dendrimers by enzymes. The reduced degradability may cause the accumulation of the lysine dendrimer when injected to a living body. The research project aims to produce new enzyme-degradable dendrimers for biomedical application. In order to achieve the goal, a series of lysine dendrimers which remain the ε-amino group of each lysine was prepared. The study on the degradation of the novel lysine dendrimers by enzymes was also planned to evaluate the effect of the ε-amino group on enzymatic degradation.The trimer and te … More tramer composed of glycine and lysine were designed as building blocks for the novel lysine dendrimers. The peptide oligomers were prepared by conventional solid-phase synthesis on the acid sensitive trityl-resin. The α-and ε-amino groups of the peptide oligomers were protected by 9-fluorenylmethoxycarbonyl (Fmoc) and t-butoxycarbonyl (BOC) groups, respectively. The structure of the peptide oligomers was confirmed by NMR and MALDI-TOF MS spectroscopic measurements. The lysine dendrimers were prepared using the peptide oligomers as building blocks by Fmoc solid-phase synthetic strategy on Wang-resin. The final cleavage by trifluoroacetic acid resulted in the formation of the deprotected lysine dendrimers which had the ε-amino groups on each building unit. The each generation one and two dendrimer purified by preparative HPLC showed a single peak by analytical HPLC. The molecular weight of the dendrimers was confirmed by the MALDI-TOF MS measurement. It was also observed that the cleavage of the BOC groups required prolonged reaction time in comparison with the case of deprotection of BOC groups for conventional peptide syntheses. The preparation of high-generation dendrimers from the peptide oligomers and the enzymatic degradation study have been postponed due to the difficulty in mass production of the peptide oligomer. Although the term of this research project supported by Grand-in-Aid for scientific research c was finished, the project has continuously been pursued in order to create new enzyme-degradable dendrimers. Less