羥脯胺酸醣化修飾對膠原蛋白穩定性與自組裝之影響

The effects of glycosylated (2S,4R)-hydroxyproline on collagen stability and self-assembly

黃佩雯(Huang, Pei Wen)

指導教授 ： 洪嘉呈

國立清華大學/理學院/化學系/碩士(2015年)

摘要

膠原蛋白是哺乳動物中含量最豐富的蛋白質，現今已廣泛應用於生醫材料上，為增加其應用性，許多研究者將不同的官能機修飾在膠原蛋白上，或是利用非共價作用力幫助膠原蛋白自組裝成更大的分子來探討其潛在應用，膠原蛋白的特色之一由個別的聚脯胺酸第二型結構 ( PPII ) 所形成之三股螺旋。另一方面，醣類在生理上的應用，生物體內的機制，扮演著重要的角色。
本研究的主題為以膠原蛋白為基底，將一個經過1.2,3,4,6-penta-O-acetyl-β-D-galactopyranoside修飾的羥脯胺酸，以固相胜肽合成法置入膠原蛋白胜肽中，合成一系列醣化修飾的膠原蛋白胜肽，探討醣化對膠原蛋白三股螺旋熱穩定性與其自組裝結構之影響，也利用了分子模擬探討其結構變化。
經由 CD 測量發現，修飾半乳糖後所形成的胜肽鏈，不論修飾在哪一個位置，其所形成之三股螺旋熱穩定度皆會下降。而分子模擬結果發現，其半乳糖之間的距離過大，並不會有作用力的形成。然而醣化後的膠原蛋白胜肽會加速自組裝形成大型結構。再者，由 TEM 的結果發現，有接上半乳糖的胜肽鏈，其自組裝所形成的纖維寬度都較沒修半乳糖的胜肽鏈來的大，因此可知半乳糖修飾有助於膠原蛋白胜肽鏈的自組裝。

關鍵字

膠原蛋白 ； 半乳糖

並列摘要

Collagen, the most abundant protein in mammalian tissues, has been widely used in biomedical materials. Many researchers have been performing various modifications on collagen to increase its applicability. Different non-covalent interactions were also applied to promote the self-assembly of collagen into higher order structure. Collagen is a right-handed triple helix, and each helix is a left-handed polyproline type II structure containing many (X-Y-Gly)n repeats. On the other hand, carbohydrates are a necessity to organism and play an important role in biological functions.
In this work, we modified (2S,4R)-hydroxyproline with 1.2,3,4,6-penta-O-acetyl-β-D-galactopyranoside and synthesized a series of collagen-related peptides containing this modified amino acid to study the consequences of glycosylation on collagen stability and self-assembly.
CD measurements indicate that glycosylation will destabilize the collagen triple helices. However, TEM shows that the modification promotes the self-assembly of collagen-related peptides into higher-order structures, suggesting that glycosylation could enhance the interactions between collagen-related peptides to speed their assembly.

並列關鍵字

collagen ； galactose

參考文獻

34. 張峻銘. (2014) 膠原蛋白模擬胜肽對貝它類澱粉蛋白聚集影響的探討, (碩士學位論文), 國立清華大學化學系.

1. Bella, J., Brodsky, B., and Berman, H. M. (1995) Hydration structure of a collagen peptide, Structure 3, 893-906.

3. Griffon, N. B., V.; Dieryck, W.; Domoulin, A.; Paginer, J.; Poyart, C.;Marden, M. C. (1998) tetramer-dimer equilibrium of oxyhemoglobin mutants determined from auto-oxidation rates, Protein Sci. 7, 673-680.

4. Prockop, D. J. K., K. I. (1995) Collagens: molecular biology, diseases, and potentials for therapy, Annu. Rev. Biochem. 64, 403-434.

5. Prockop, D. J. (1998) What holds us together? Why do some of us fall apart? What can we do about it?, Matrix Biol. 16, 519-528.