根據文獻(van Dyke & Dervan, 1984)指出，echinomycin此葯物 A對
於5'-NCGN-3'特定序列有較強的結合能力。本報告就選取其中的非迴文對
稱序列(non-palindromic sequence);[d(TCGT)．d(ACGA)]，及其與
echinomycin 作用後的複合物(complex)為對象，使用NMR實驗數據，特別
使用其中2D-NOESY所提供質子間距離關係，來做其局部立體結構特徵上的
探討。再透過電腦軟體，做有限制條件的分子動態模擬 (restrained
molecular dynamics) 及能量最小化(restrainedenergy理想的(
optimal)3-D分子結構。結果發現, 所有未結合前的DNA採Watson -C
minimization)計算，找出DNA分子的最rick的鹼基配對；在形成複合物後
，T1-A8採Watson-Crick的鹼基配對，而T4．A5則採Hoogsteen的鹼基配對
。DNA與藥物結合後之特殊構形與DNA之序列有關，當其排列為Pur-CG時，
會採Hoogsteen配對，而排列為Pur-CG時，則不會。

We report on two-dimensional proton NMR studies of echinomycin
co mplexed with non-palindromic sequence [d(TCGT)．d(ACGA)]
duplex in aqueous solution. The sequence specificity of
echionmycin bind ing to nucleic acids had been probed with the
chemical footprinti ng on DNA pBR 322 restriction fragments.
(van Dyke & Dervan, 1984 ). The footprinting experiments
demonstrated that the strongest e chinomycin binding sites are
cented about 5'-NCGN-3' sequence. We utilized the NMR
experiments, especailly the NOESY crosspeaks in tensity to
reveal the interprotons distance, to elucidate the cr ude
local structures of the binding complex. Finally, we using co
mputer graphics model techniques, restrainted molecular
dynamics and restrainted minimization calculations to obtain
the optimal t hree-dimensional sturcutre of the DNA-drug
binding complex. We de monstrated that all base pairs adopt
Watson-Crick pairing for fre e DNA duplex. In the case of
binding complex and the T1．A8 base pairs would adopt Watson-
Crick pairing while theT4．A5 base pairs adopt Hoogsteen
pairing. We then concluded that the better resul t were related
to the sequence of base stacking. The Pur-CG stac king would
adopt Hoogsteen pairing while the Pyr-CG stacking woul d adopt
Watson-Crick pairing.
We report on two-dimensional proton NMR studies of echinomycin