針對β-葡萄糖水解酶發展酵素表面及活性中心內標示的兩種探針以應用於蛋白質體學研究

Developing exo- versus endo-Labeling Probes for β-Glucosidase Towards the Application in Proteomics

陳玉芬(Yu-Fen Chen)

指導教授 ： 陳昭岑

國立臺灣大學/理學院/化學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.02427

摘要

在生物體內，醣類衍生物被視為訊息攜帶分子，涉及免疫反應、病毒感染，以及細胞間的辨識與訊息傳遞等生物功能，其重要性使得醣質生物學（glycobiology）成為生命科學的新焦點。而醣苷水解酶在控制生物體內醣類的代謝、生成，以及細胞表面分子辨識上扮演了重要角色，若活性失調可能引起多種疾病。因此，這類酵素的研究將有助於臨床上疾病診斷與治療、藥物開發及病理瞭解等。在本論文中，是以商業上可購得來自杏仁的β-葡萄糖水解酶（β-glucosidase）為研究對象。並利用ABPP（activity-based protein profiling）策略發展其活性標示探針，以期能應用於蛋白質體學（proteomics）的研究上。我們成功發展了對β-葡萄糖水解酶具有標示潛力的光親合性（photoaffinity）活性標示探針B-1（為酵素表面標示的探針），以及以酵素催化機制為基礎的（mechanism-based）活性標示探針C-1（為酵素活性中心內標示的探針）。其中，探針B-1的設計包括了S-linked β-D-葡萄糖衍生物、光反應基團，以及生物素標籤。這三重功能性探針的設計是希望探針在與目標蛋白質專一辨識後，經由照光反應可以在活性中心附近形成共價鍵結，再由生物素的標籤輸出訊號。在探針B-1標示蛋白質的相關實驗中，已證實其能與目標酵素活性中心親合性結合，並以共價鍵連結。另外，探針C-1的設計包括了epoxyalkyl glucosides衍生物和疊氮（azido）基團。其設計是希望藉由酵素催化過程與探針上反應基團epoxide形成共價鍵結，再利用疊氮基團進行click反應連接標籤。而在標示蛋白質的相關實驗中，則發現缺乏epoxide的對照物C-1a標示效果較探針C-1佳，但目前仍未知其與酵素形成共價鍵的機制。此外，這些探針進行蛋白質標示的結果顯示配基為S-linked的探針B-1專一性較不高，而具有天然O-linked配基的探針C-1對β-葡萄糖水解酶具有專一性。最後，這些探針組裝式的合成提供了未來其結構改良的簡便性，可再經由配基或反應基團的置換等，來提升探針的專一性標示。

關鍵字

β-葡萄糖水解酶蛋白質體學 ； ABPP ； 光親合性 ； 以酵素催化機制為基礎的

並列摘要

In organisms, saccharide derivatives are deemed as information carriers, involving biological functions, such as immune response, virus infection, cell-cell communication and signal transduction, etc.. Their biological importance makes glycobiology become a new focus of life sciences. Among them, glycosidases play important roles in controlling saccharide metabolism, anabolism and cell surface molecule recognization. Any imbalance in their activities may result in many kinds of diseases. So the study of this kind of enzymes will benefit to the clinical diagnosis/treatment, drug discovery and understanding pathology etc. In this thesis, the commercially available β-glucosidase from almonds is used as the research model. Various ABPs (activity-based probes) were developed to label the enzymes hoping to extend the strategy to study proteome. We have succeeded in developing photoaffinitity ABP B-1 (exo-labeling probes) and mechanism-based ABP C-1 (endo-labeling probes), which exhibit potential in labeling β-glucosidases. Probe B-1 consists of a S-linked β-D-glucose derivative, a photoreactive group, and a biotin tag. This trifunctional probe is designed to form the covalent bond by photoreacting group near the active site once the probe and the targeted protein were bound together specifically and the biotin tag could be regarded as output for facile purification. In the protein labeling experiment employing the probe B-1, it showed that the probe can recognize the active site of the targeted enzyme specifically via a covalent bond. The probe C-1 is composed of a epoxyalkyl glucoside derivative and an azido group. A covalent bond between the enzyme and epoxide reactive group forms first, and then an azido group could react with the tag by click reaction afterwards. The protein labeling experiment using control C-1a, which has no epoxide, displayed good labeling effect, despite that the labeling mechanism is not clear. Moreover, probe B-1, which has S-linked ligand, cannot specifically label β-glucosidases, whereas probe C-1, which has native O-linked ligand, can specifically label β-glucosidases. To summarize, the study has laid the foundation for the development of ABPP (activity-based protein profiling) probes. Moreover, the modules nature of the probe designs offer molecular simplicity and concision. The specificity can be improved either by changing the ligand or reactive groups.

並列關鍵字

β-glucosidase ； proteomics ； ABPP ； photoaffinity ； mechanism-based

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