核酸分子之重要性視為所有生物分子之核心,但對其深入的結構及認知至
今卻仍不甚清楚.過去核酸化學多由X-ray晶體繞射建立架構,然符合生理
狀態的分子乃是處於水溶液中,故運應用核磁共振儀來探究分子在溶液中
的結構.隨著特定序列性之因,序列的組成與列會影響構形,尤其在與藥物
鍵結時,序列影響其與藥物的鍵結很大.本報告對非迴文對稱序列的四個鹼
基對DNA分子d(TGGT)+d(ACCA),以二維的COSY & NOESY實驗,運用felix軟
體做數據處理.將譜圖上各交叉峰判定,並依交叉體積與距離的關係,將結
構做半定量的分析;見鹼基上為Watson-Crick構形,醣基上則屬2'-endo乃
B-form DNA 結構.再配合實驗數據,利用電腦做分子模擬及能量計算.在與
藥物鍵結方面,DNA與echinomycin形成錯合物比例僅61%,以微弱凡得瓦爾
力鍵結.

The structure of nucleic acid molecules is of central
importance in molecular bioiogy.However,until recently their
detailed stru- cture remain obscure.While the detailed
structural information of these important molecules are existed
through X-ray diffraction studies,all molecules are existed in
solution state in vivo.Thus we utilized high resolution
solution state NMR techniques to stud y the molecular structure.
In this report,we used two dimensional COSY & NOESY
spectroscopy to study sequence specific echinomycin binding
site on DNA a non-complemntric tetramer d(TGGT)+d(ACCA).W e
untilize the computer molecular modeling techniques,such as res
trained molecular dynamic(rMD)and restrained energy
minimization (rEM)experimential NOE data as constraints to
further refine our DNA structure.We demonstrated that the base
pairs adopt Watson-Cr ick base pairing ,while sugar adopt
2'-endo conformation.All stru ctural features are belong to B-
form DNA structue families.The DN A binding with echinomycin at
ratio of only 61%,with weak van de r waal force.
The structure of nucleic acid molecules is of central