合成鼠李醣三醣重複單元以擬似丁香假單胞菌LPS的抗原決定簇之研究

Synthesis of rhamnosyl trisaccharide repeating unit to mimic the antigen determinant of Pseudomonas syringae lipopolysaccharide

王姮雁(Heng-Yen Wang)

指導教授 ： 俞鐘山

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(2006年)

摘要

化學上的研究顯示出，P. syringae品種LPS中，OPS的部分是呈現直鏈狀或是分支狀的結構。直鏈狀結構其主鏈骨架是由L-、D-或是L-/D-rhamnose構成；而分支狀結構是在rhamnose主鏈上，連結上不同或相同的的醣取代基所構成。
基於上述各點，本研究之方向為合成出丁香假單胞菌中主鏈的部分，即Rha(1→3) Rha(1→2)Rhap的三醣重複鍵結結構。利用imidate的予體活化方式，並加以控制醣基化反應中各項變因以及條件，達成合成丁香假單胞菌LPS中，OPS以rhamnose為主鏈的生物特性結構。合成的方式，是由具有拉電子保護基的醣14當作予體連結C-1位置具有硫保護基的予體19成為雙醣，而後將還原端醣的硫保護基去除並加以活化，再連結受體18，如此一一連結而製備出三醣23的結構。予體的部分，製備出具有Ac、Bz和Bn保護的單體，從反應活性及合成策略的考量，選擇了以推電子保護基Bn形式的予體14作為雙醣合成的架構。而受體部分，C-2和C-3經由一個打叉的保護再選擇性去除C-2或是C-3的保護，可以輕易地塑造出予體19以及18的先驅物。使得合成Rha(1→3) Rha(1→2)Rhap架構的三醣更加地便利可行。

關鍵字

鼠李醣

並列摘要

Chemical studies reveal that the structure of OPS are linear or branched among P. syringae strains. The linear backbone is composed of L-, D-, or both L-and D-rhamnose. The branch OPS is composed of linear backbone with homogenous or hetrogenous saccharide substitution.
Above all, the pivot issue of this thesis is to synthesize the linear backbone motif of P. syringae, a trisaccharide structure of Rha(1→3) Rha(1→2)Rhap. Utilizing the anomeric center activation manner of imidate and manipulating all factors and condition during glycosylation, we accomplish the synthesis of rhamnose linear backbone, unique biological feature of OPS , in the P. syringae LPS. Our synthesis strategy is to prepare disaccharide which is composed of electron-donating group protected donor 14 and anomeric center thio protected acceptor 19. The reducing end of the disaccharide is follewed by deprotection and activation of anomeric center, and then perform glycosylation with acceptor 18 for further synthesis of trisaccharide structure 23. As for donor, having synthesized Ac, Bz and Bn protected donors, we choose electron-donating Bn type donor 14 as buiding block of disaccharide synthesis for the sake of reactivity and synthesis strategy consideration. As for acceptor, through a acetal protection on C-2 and C-3 follewed by selective deprotection of C-2 or C-3, we could easily create precursor of aceeptor 19 and 18. It makes the synthesis of
Rha(1→3) Rha(1→2)Rhap feature trisaccharide to be more facile.

並列關鍵字

LPS

參考文獻

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