合成以胜肽結合Poly(amidoamine)的樹枝狀高分子當作人工消旋酶

Synthesis of Peptide Conjugated Poly(amidoamine) Dendrimer as Artifical Racemerase.

林侑陞(Yu-Sheng Lin)

指導教授 ： 王英基

高雄醫學大學/生命科學院/醫藥暨應用化學研究所/碩士(2010年)

摘要

磷酸吡哆醛是維他命B6中的一種，也是唯一在人體中具有活性的，它能藉由與離胺酸進行結合停留在酵素中，進而進行各種催化反應，如消旋反應。基於之前的研究，我們發現在PAMAM樹枝狀高分子表面上修飾胜肽，可以結合磷酸吡哆醛，本實驗基於此一結果設計出不同的胜肽以修飾樹枝狀高分子，希望得到更具結合力的樹枝狀高分子，此外也測試這些樹枝狀分子的消旋能力。因此我們欲合成出以三胺基酸所組成的短鏈胜肽，設計成Phe-Lys-X的序列，X為色胺酸、組胺酸或酪胺酸；以前後具有芳香環的型式，藉由夾心的方式對與離胺酸鍵結的磷酸吡哆醛以???{?? interaction而加強鍵結能力。但在合成胜肽上遇到溶解性不佳的情況，最後以更換保護基解決此問題，進而將胜肽修飾在PAMAM樹枝狀高分子。
測試消旋反應則是以(G;Y)-dendri-PAMAM-(APO-Phe-Lys)n來當作試劑，選用鍵結常數最小的G4與最大的G5、G7，在混合磷酸吡哆醛與左旋苯丙胺酸後七天，可以得到右旋苯丙胺酸，因此我們以APO-Phe-Lys胜肽修飾PAMAM樹枝狀高分子是有催化消旋反應的能力。

關鍵字

樹枝狀高分子 ； 磷酸吡哆醛 ； 消旋

並列摘要

Pyridoxal 5′-Phosphate (PLP) is the active member of of vitamin B6. PLP are known to perform numbers of reactivities in a variety of enzymes in which the lysine is a conserved residue for harboring PLP via Schiff base moiety. This is also known as external aldimine. During the course of reaction, the inbound substrate will form new Schiff base with PLP, and known as external aldimine. The exchange between external and internal aldimine is important for the demonstration of reactions. Base on the previous experimental results, we design a tripeptide involving lysine to modify the surface of PAMAM dendrimer for binding the Pyridoxal 5′-Phosphate. The designed peptides are Phe-Lys-X. The aromatic ring of phenylamine enhances the binding through PLP by?n???{???ninteraction. By the same reason, histidine, tryptophan, or tyrosine are chosen to be the third residue. During the synthesis of peptide, we found the protecting group is crucial to the solubility of those tripeptides. Those with Fmoc protecting group exhibit poor solubility.
(G; 4, 5, 7)-dendri-PAMAM-(APO-Phe-Lys)n was selected for the investigation of rasemization. Under basic condition, the racemization was monitered by HPLC analysis. This result proves the ability of those synthetic dendrimers as catalyst of racemization.

並列關鍵字

PAMAM dendrimer ； PLP ； racemization

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