利用CD和NMR研究合成的神經胜肽片段hPP【17-24】之結構

Conformational studies of synthesized neuropeptide fragment hPP【17-24】by CD and NMR

吳明儒(Ming-Ju Wu)

指導教授 ： 李長欣

淡江大學/理學院/化學學系碩士班/碩士(2008年)

https://doi.org/10.6846/TKU.2008.00465

摘要

Human Pancreatic Polypeptide（hPP）隸屬於NPY家族（Neuropeptide Y Family）。包含幾項特徵：有36個胺基酸殘基；C端以NH2來做結束（C-terminally amidated）；且具有PP-fold。hPP與Y4或是Y5 Receptor結合後，在中樞神經系統中扮演著促進食物的攝取以及提醒胃空了。結構上，C端為α-helical部分而N端有polyproline helix，polyproline helix會彎曲回來與α-helical相連接，形成特有的PP-fold.結構。hPP在水溶液中以dimer的方式存在，當它與micelle作用時，便形成monomer。Monomer結構對作用中的hPP而言更顯得重要。透過短片段序列減少dimer的發生機會，並研究短片段狀況下是否依然具有規則結構。
我們研究hPP【17-24】序列，位於hPP α-helical部分。利用SPPS來合成hPP【17-24】，透過HPLC分離及純化並送測Mass鑑定分子量。最後利用CD及2D NMR實驗來研究hPP【17-24】在100%H2O與50%TFE / 50%H2O溶液下的結構。結果發現hPP【17-24】在兩種溶液中均喪失α-helical結構。hPP【17-24】在100%H2O中以Random coil形式存在；在50%TFE / 50%H2O溶液下逐漸有規則結構形成。

關鍵字

核磁共振 ； 圓二色光譜儀 ； 神經胜肽 ； 固相胜肽合成法

並列摘要

The human pancreatic polypeptide(hPP), a 36-residue, polypeptide hormone is a member of the neuropeptide Y(NPY)family. In the central nervous system PP promotes food intake and gastric emptying by activation of the Y4 and probably Y5 receptors. The C-terminal is a well-defined α-helical region and the N terminus is an extended polyproline helix which bent back onto the the C-terminalα-helix. The structural motif of pp has been named as the PP-fold. hPP in solution exists as a dimer and when bound to micelle, it exists as a monomer. Therefore, to elucidate the monomer structure is important. Short peptide fragment may avoid dimmer formation and reveal the folding dynamoics of hpp.
We studied hPP[17-24] ,of α-helical region, and used SPPS method for synthesizing the residues17-24.Isolation and purification were performed by HPLC and the molecular weight were made sure by Mass. The conformation and dynamics of hPP[17-24] in different solvent condition is studied by CD and 2D NMR experiment. Conformation of hPP[17-24] exists as a random coil in 100%H2O and become more regular in 50%TFE / 50%H2O of hPP[17-24].

並列關鍵字

2D NMR ； CD ； NPY ； PP ； SPPS.

參考文獻

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