拥挤试剂PEG2000对不同拓扑结构类弹性蛋白相变的影响

类弹性蛋白（Elastin-like polypeptides，ELPs）是属于弹性蛋白中的一种且具有温控性的生物大分子，本文研究拥挤试剂对不同拓扑结构ELPs相变温度的影响，利用温控-紫外分光光度计研究其相变特性，结果发现，随着PEG2000浓度的增加，T-E-F的相变温度下降11.9~17.1℃；在固定Tadpole-like-E浓度下，随着PEG2000浓度的增加，Tadpole-like-E的相变温度降低11.5~16℃，其中，25 μmol/L的Tadpole-like-E其相变速度缓慢；ELPs浓度越大，其相变温度降低愈大，且PEG2000影响ELPs相变温度的趋势与ELPs的拓扑结构关系不大。另外，在简单的PBS缓冲溶液中加入PEG2000，可以使E-C在浓度＜0.5 mol/L的Na2CO3中发生相变，且随着PEG2000浓度的增加，E-C相变温度逐渐降低。本研究为今后ELPs在复杂体系的应用提供前期的基础研究。

The Effects of Crowding Agents PEG2000 on the Phase Transition of Elastin-like Polypeptides in Different Topological Structures

Elastin-like polypeptides (ELPs) are typically recognized as elastin. They are biological macromolecules with temperature-controlled characteristics. This paper focuses on studying the effects of phase transition temperatures of ELPs with different topological structures with crowding reagents PEG2000 by using UV spectrophotometers. The results showed that when PEG2000 concentration increased, the three-armed ELPs-Foldon (T-E-F) phase transition temperature decreased 11.9℃~17.1℃. At a certain concentration of Tadpole-like-ELP (Tadpole-like-E), the Tadpole-like E phase transition temperature decreased 11.5~16℃ with the increase of PEG2000 concentration. In particular, when Tadpole-like E was at 25 µmol/L, its phase transition behavior was slow. The higher the concentration of ELPs, the further decrease of the phase transition temperature of ELPs. In addition, the effects of PEG2000 on changing the ELP transition temperature had little relationship with different topologies. Furthermore, PEG2000 was shown to be able to stimulate the phases transition of ELPs-SpyCather (E-C) under a low concentration of Na2CO3 solution (<0.5 mol/L). With the increase of the PEG2000 concentration, the phase transition temperature of E-C decreased. This study provides the basis for the application of ELPs in complex systems in the future.