Self-assembling Peptides

拟议研究计划的目标：该研究计划的总体目标是开发多功能、可注射的水凝胶，这种凝胶对酶的存在动态反应，以达到控制治疗分子释放的明确目的。尤其令人感兴趣的是多肽、蛋白质和DNA的受控释放。 导致纳米纤维形成的基本机制还没有被清楚地阐明(RADA)4.以前的工作(PNAS，2005,102(24)：8414 8419)已经表明，多肽从球状颗粒自组装成微米长的纳米纤维发生在60秒内；这个时间框架似乎与物理解释不符。关于N-末端氨基酸的加成，我们观察到(在制备中)氨基酸化学及其随后的水合状态可以极大地影响这种组装过程。既然这两个组分已被确定为对纳米纤维的形成至关重要，进一步的工作将集中在阐明改变实际氨基酸化学组成的影响，以了解单个组分在自组装过程中所起的作用。此外，为了将这些系统应用于受控药物输送，我们之前的工作表明，N-末端氨基酸可以专门用于改变这些高水合水凝胶中不同水类型的群体大小：非冷冻结合、冷冻结合和自由结合。尽管人们努力了解溶液中理想化多肽结构域的酶活性(Biomaterals，2011，32(5)：1301-1310)，但很少或根本没有研究复杂水凝胶结构中的酶活性，其中纳米纤维的存在以及水的类型和区域粘度可能会影响酶的表观活性。这些主题将在这笔赠款中进一步概述。 这项工作的新颖性和对一个或多个领域的预期意义：预计这项工作将为理解RADA4纳米纤维自组装所涉及的物理化学方面提供一个框架，并有望提出一种解释这些分子快速组装的机制。将这些水凝胶中的水结构和区域粘度关联起来，应该可以更好地了解纳米纤维化学对酶的流动性和活性的影响。尽管一些工作已经研究了酶作为水的函数的作用，但在水凝胶领域了解这一点对于进一步了解复杂介质中的酶作用将是至关重要的。

Objectives of the proposed research program: The overall objective of this research program is to develop multifunctional, injectable, hydrogels that are dynamically responsive to the presence of enzymes for the express purpose of controlling the release of therapeutic molecules. Of particular interest is the controlled release of peptides, proteins, and DNA. The fundamental mechanisms leading to nanofiber formation have not been clearly elucidated for this (RADA)4. Previous work (PNAS, 2005, 102(24):8414 8419) has shown that peptide self-assembly into micron long nanofibers, from globules, occurs within 60 seconds; a time frame that seems to defy a physical explanation. With respects to the addition of N-terminal amino acids, we have observed (in preparation) that amino acid chemistry, and their subsequent hydration state, can greatly affect this assembly process. Now that these two components have been identified as being crucial to nanofiber formation, further work will focus on elucidating the effect of altering the actual amino acid chemical makeup to understand the role individual components have on self-assembly process. Furthermore, in order for these systems to be applied for controlled drug delivery, our previous work has shown that N-terminal amino acids can be used to specifically modify the population size of different water types within these highly hydrated hydrogels: non-freezing bound, freezing bound, unbounded free. Despite efforts understanding the enzymatic activity toward idealized peptide domains in solution (Biomaterials, 2011, 32(5): 1301-1310) little to no work has been conducted on investigating enzymatic activity within the complex hydrogel structure, where the presence of the nanofiber, as well as types of waters, and regional viscosity may affect the apparent activity of enzymes. These topics will be further outlined within this grant. Novelty and expected significance of the work to a field or fields: It is expected that this work will provide a framework for understanding the physicochemical aspects involved in the self-assembly of RADA4 nanofibers, hopefully presenting a mechanism that explains the rapid assembly of these molecules. Correlating water structures and regional viscosity in these hydrogels should allow for a better understanding of the effect nanofiber chemistry has on the mobility and activity of enzymes. Although some work has investigated enzyme action as a function of waters, understanding this in the realm of a hydrogel will be crucial to furthering a biophysical understanding of enzyme action in complex media.