己醛醣酸鹽水解酵素受質與抑制劑的合成

Synthesis of the α-L-iduronidase substrate and inhibitors

奚偉恩(Wayne Hsi)

指導教授 ： 羅禮強

共同指導教授 ： 鄭偉杰

國立臺灣大學/理學院/化學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.10274

摘要

己醛醣酸鹽水解酵素為內切型醣水解酵素，它的功能在於切除葡萄糖胺多醣體內L-艾杜醣,D-葡萄糖胺之間的1,4-醣苷鍵。已知文獻中鮮少提及己醛醣酸鹽水解酵素的抑制研究，因為L-艾杜醣，L-艾杜醣酸相關的酵素受質難以從天然物取得，需要人工合成，價格昂貴。因此有必要開發新方法取得己醛醣酸鹽水解酵素受質，以降低成本、自給自足。
己醛醣酸鹽水解酵素是罕見遺傳疾病「黏多醣儲積症第一型」的致病酵素。
我的合成路徑從1,2:5,6-雙異亞丙基-α-D-五環葡萄糖，經五號碳立體組態翻轉取得3-OBn-L-艾杜醣的關鍵中間體，透過三氯乙酰亞胺酯與4-甲基-7-羥基香豆素作醣化反應，TEMPO選擇性氧化一級醇，取得了己醛醣酸鹽水解酵素的螢光受質。
另一方面，為模仿此酵素進行醣水解反應時的過渡態，設計了兩個二號碳帶亞甲基胺的吡咯啶胺醣骨架，從五圓環硝中間體，經氮原子保護和TEMPO/NaOCl/NaClO2選擇性氧化，合成五圓環硝酸鹽。最後在其中一個吡咯啶胺醣骨架透過醯胺鍵接上一個酸，以用於後續酵素抑制性研究。

關鍵字

亞胺醣 ； 環硝 ； 艾杜糖 ； 己醛醣酸鹽水解酵素 ； 抑制劑

並列摘要

α-L-iduronidase (IDUA), an endoglycosidase, cleaves the 1,4-glycosidic bond between L-iduronic acids (L-IdoA) and D-glucosamine (or D-galactosamine) in heparin and heparan sulfate. The inhibition study of IDUA is important but rarely mentioned in the literature because materials such as L-Idopyranose and L-IdoA are not commercially available. And substrates are expensive. Thus, an economical source of IDUA substrate is needed.
Currently, IDUA has been found to involve with a genetically inherited lysosomal storage disease, mucopolysaccharidosis I (MPS1).
A synthetic route started from 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, through C-5 inversion of configuration gave a key intermediate 3-OBn-L-idopyranose, followed by trichloroacetimidate-mediated glycosylation with 4-methylumbelliferone and selective primary alcohol oxidation by TEMPO catalyst to give the 4-methylumbelliferyl α-L-iduronide (4MU-α-IdoA) as a fluorogenic substrate for IDUA.
To mimic the oxocarbenium ion generated during IDUA hydrolysis, 2-(aminomethyl) pyrrolidine iminosugar scaffolds were prepared using a five-membered chiral cyclic nitrone as a key intermediate, followed by N-protection and selective oxidation by TEMPO/NaOCl/ NaClO2 to give the aza-L-iduronic acid analogs. An acid was coupled with a scaffold to. diversify at primary amine as a model for further inhibition study.

並列關鍵字

α-L-iduronidase ； inhibitor ； cyclic nitrone ； 4MU-α-IdoA

參考文獻

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