利用 Cation-π 作用力誘導膠原蛋白異源三股螺旋形成及膠原蛋白胜肽自組裝之探討

Using Cation-π Interactions to Form Heterotrimeric Collagen Helices and Assemble Collagen-Related Peptides

高堂畯(Tang-Chun Kao)

指導教授 ： 洪嘉呈

國立清華大學/理學院/化學系/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00206

摘要

膠原蛋白是動物體內組織中含量最多的蛋白質，其特殊的構造是由包含了重複 X-Y-Gly 序列的三條左旋第二型聚脯胺酸胜肽鏈，沿著相同軸方向纏繞成的一右旋三股螺旋結構。第 Ⅰ 型膠原蛋白，為天然膠原蛋白含量最多的一種型態，其為異源三股螺旋結構，因此探討異源三股螺旋結構之膠原蛋白模擬胜肽能夠更接近於自然界中的情形。在這裡的實驗中我們利用 cation-π 作用力幫助合成的膠原蛋白模擬胜肽纏繞成異源三股螺旋結構，CD 及 NMR 測量結果顯示 (POGPRG)3(POG) & (POGFOG)3(POG)、 (POGPRG)3(POG) & (POGFOG)3(POG) & (POG)7 混合胜肽溶液可形成單一的異源三股螺旋結構，得到的 Tm 值分別為 26 ºC 及 27.5 ºC，且沒有伴隨各自成份的同源三股螺旋產生，所以利用設計過的胜肽序列，藉由不同胜肽鏈間的 cation-π 作用力能夠使我們得到穩定的膠原蛋白異源三股螺旋結構。
在先前實驗室研究我們了解在兩端的 cation-π 作用力能夠促進 RG(POG)10F 快速聚集成纖維結構，在這裡我們進一步合成 (POG)4(PRG)(FOG)(POG)4、(POG)3(PRG)(POG)2(FOG)(POG)3、(POG)2(PRG) (POG)4(FOG)(POG)2、RG(POG)3(PRG)(POG)2(FOG)(POG)3F，研究不同位置的 cation-π 作用力對其聚集過程的影響，turbidity 及 DLS 量測顯示股內的 cation-π 作用力並無明顯促進它們聚集成更大的超分子纖維結構，此結果也指出當將 (PRG) 和 (FOG) 序列崁入整個膠原蛋白胜肽的中間時，可能因為 arginine、phenylalanine 的置入使得結構的立體障礙變大而無法形成強的 cation-π 作用力，進而阻礙膠原蛋白三股螺旋間的堆疊。

關鍵字

膠原蛋白 ； 異源三股螺旋 ； Cation-π 作用力 ； 膠原蛋白胜肽自組裝

並列摘要

Collagen is an important structural component of tissues in animals. It has an unique right-handed triple helix consisted of three left-handed polyproline II like chains which are composed of X-Y-Gly repeats in the sequence. TypeⅠcollagen, a heterotrimer, is the most abundant form, and thus using heterotrimeric helices can be more appropriate to mimic nature collagen. In this work, we used cation-π interactions to assist collagen-related peptides to fold into heterotrimers. CD and NMR measurements indicate that (POGPRG)3(POG) & (POGFOG)3(POG), (POGPRG)3(POG) & (POGFOG)3(POG) & (POG)7 mixed peptide solution could form a single heterotrimeric helices with Tm values of 26 and 27.5 ºC respectively, and no homotrimers were found. The results demonstrate that heterotrimers could be formed by interchain cation-π interactions.
We have previously shown that terminal cation-π interactions can promote RG(POG)10F to rapidly assemble into fibrils. Here we further synthesized (POG)4(PRG)(FOG)(POG)4, (POG)3(PRG)(POG)2(FOG)(POG)3, (POG)2(PRG) (POG)4(FOG)(POG)2, and RG(POG)3(PRG)(POG)2(FOG)(POG)3F to study the position dependent effects of cation-π interactions on their self-assembly process. Turbility and dynamic light scattering measurements showed that such designs and arrangements do not significantly promote the assembly process. The results imply that the PRG and FOG triplets in place of POG in the middle of a collagen related peptide may impose steric effects through the bulky side chains of arginine and phenylalanine residues, which prevent the formation of strong cation-π interactions and retard the packing between collagen triple helices.

並列關鍵字

Collagen ； Heterotrimeric helices ； Cation-π Interactions ； Assemble Collagen-Related Peptides

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