三链DNA d(A)10·2d(T)10-溴乙锭的能量转移

在水溶液中,由两条互补的单链DNA 构成的双螺旋沿着大沟有额外的氢键受体和给体,这些给体和受体暴露于周围环境,从而可以和专一性的结合分子(如蛋白)发生相互作用,形成特异性的复合物,也可以与另外的单链DNA 分子结合形成三链DNA.近年来,由于越来越多的证据表明:三链DNA 能在细胞体内形成,并具有多种生物学功能而引起了人们的广泛关注,成为生物化学、分子生物学和基因工程领域的一个前沿课题.通过三链DNA的形成,寡聚核酸可以参与基因转录过程,但是在生理条件下,三链DNA 的稳定性似乎是

THE ENERGY TRANSFER FROM TRIPLEX dA_(10).2dT_(10) TO THE BOUND ETHIDIUM BROMIDE

The energy transfer from triplex dA_(10)·2dT_(10) or duplex dA_(10)·dA_(10) to ethidium bromide in the 10 mmol·L~(-1) phosphate buffer (pH=7.1) has been investigated. The apparent relative fluorescence quantum yield as a function of excitation wavelength is observed, but the increase in quantum yield in case of the triplex is lower than that for the duplex. This result not only provides strong evidence for intercalative binding of ethidium to both duplex and triplex forms of dA_(10) and dT_(10), but also indicates that binding to the triplex form results in substantially smaller energy transfer than binding to the duplex.