4-1.CGG 重複序列與插入 AGG 的 CGG 重複序列可能之構型
過去 Usdin 團隊研究指出，G-四聯體可能在 CGG 重複序列的不正常擴張 扮演重要角色[39]，我們透過單分子實驗與圓二色性光譜對富含 CGG 的重複序 列在鉀離子濃度 150 mM 的環境下進行觀察，結果顯示皆形成髮夾型結構，該 序列在低濃度下並不會形成分子內 G-四聯體，如圖六十。先前的研究可能是在 非生理條件下進行[22]，亦或是形成分子間的 G-四聯體[18]。
圖 六十、富含 CGG 的重複序列在 150 mM 鉀離子濃度下難以形成 G-四聯體。
先前本實驗室的研究發現，當 CGG 重複序列重複次數為奇數時，主要形成 露出一個鳥嘌呤的突出髮夾型結構；重複次數為偶數時，則形成對齊髮夾型結構 [41]，兩者主要構型均無較長的突出髮夾型結構，因此我們認為有利於不正常的 擴張[26]。插入一組 AGG 後的 CGG 重複序列形成兩種主要構型，分別為露出 一組 CGG 的突出髮夾型結構和露出一個鳥嘌呤的突出髮夾型結構。奇數組 CGG 重複序列與插入一組 AGG 的 CGG 重複序列都存在兩種構型之間的轉 換，與之前實驗室發表的 (CTG)n 序列相似[4]，加上之前 Pearson 團隊研究也指
出 CGG 重複序列存在髮夾型結構上的滑動[45]，認為該構型之間的轉換應是髮
圖 六十一、CGG 重複序列複製擴張模型預測圖以及插入一組與兩組 AGG 對於動態滑動現象 的影響。
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