臺灣博碩士論文加值系統

碳酸酐酶（Carbonic Anhydrase），在生物體中主要司職於二氧化碳之水合（Hydration）與碳酸之水解（Dehydration）反應，其轉換速率（Turnover Rate）極高，每秒可達到ㄧ百萬次。此酵素之催化機制為利用活化中心所鉗合的鋅與水反應，進而促進二氧化碳還原成碳酸，以保持生物體中酸鹼值之平衡。
一般而言，碳酸酐酶之抑制劑為帶單價電荷之陰離子、陽離子與磺胺化物（Sulfonamide）；根據碳酸酐酶之x-ray三度空間晶體構造，得知在活性位置上方，多為具疏水性之官能基，因此在本實驗中，我們以合成方式建構不同立體位向之含磺胺官能基團喹口咢啉-2-酮，冀望能穩固地結合於碳酸酐酶之活化中心，進而開發出更佳之抑制劑。
首先以胺基酸之衍生物，與4-氯-3-硝基苯甲磺胺進行芳香族親核性取代反應，之後再以SnCl2將硝基還原成胺基，進行最後之分子內環化。接著將所開發出之磺胺類化合物，以p-nitro phenyl acetate 為受質，觀察抑制劑對於碳酸酐酶水解前後之變化，初步判定具有剛性之分子，對碳酸酐酶的活性比只有碳鏈之衍生物更好。

ABSTRACT

Carbonic anhydrase (CA) is an ubiquitous zinc enzyme present in prokaryotes and eukaryotes. In higher vertebrates, fourteen different CA isoforms and CA-related proteins have been isolated. These enzymes catalyze a very important physiological reaction, namely the conversion of bicarbonate (H2CO3) into carbon dioxide and water (CO2 + H2O), and vice versa. This equilibrium between carbonic acid and carbon dioxide and water is crucial to the proper functioning of numerous, commonly encountered biological and physiological processes. For instance, CO2 is not only generated from bicarbonate during respiration in metabolizing tissues and lungs, but also plays a significant role in maintaining pH and homeostasis.
Thus far, three different categories of inhibitors of CA have been discovered: anions, cations, and sulfonamides. In our study, we have designed new sulfonamide inhibitors based on the X-ray crystallographic data of CA. During the synthesis of these novel sulfonamide inhibitors, various amino acid methyl esters were first reacted with 4-chloro-3-nitrobenzenesulfonamide. Reduction of the aromatic nitro group with SnCl2, followed by spontaneous intramolecular cyclization, then afforded quinoxalinones. In the absence of inhibitors, upon the hydrolysis catalyzed by CA the p-nitrophenyl acetate substrate normally exhibits a high level of UV absorption at 400 nm. However, since a lower level of UV absorption at 400 nm was observed with the more rigid sulfonamide compounds we created, our novel sulfonamides appear to inhibit CA activity to a greater extent than alkyl sulfonamide compounds do.

目錄
第一章 碳酸酐酶之簡介
1. 背景介紹…………………………………………………01
2. 碳酸酐酶催化二氧化碳轉變為碳酸之作用機制………02
3. 碳酸酐酶之抑制劑………………………………………05
4. 參考資料…………………………………………………11
第二章 新一代碳酸酐酶抑制劑之設計與合成
1. 合成策略…………………………………………………13
2. 實驗部份…………………………………………………20
　　　　　 2.1　實驗一搬描述……………………………………..21
2.2　實驗藥品…………………………………………..22
2.3　實驗步驟…………………………………………..23
3. 結果與討論………………………………………………26
4. 結論………………………………………………………28
5. 光譜附錄…………………………………………………29
6. 參考資料…………………………………………………71
第三章 碳酸酐酶之活性測試
1. UV實驗…………………………………………………..72
2. 結果與討論………………………………………………74
3. 結論………………………………………………………76

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