Pieters J M, Mans R M, van den Elst H, van der Marel G A, van Boom J H, Altona C
Gorlaeus Laboratories, University of Leiden, The Netherlands.
Nucleic Acids Res. 1989 Jun 26;17(12):4551-65. doi: 10.1093/nar/17.12.4551.
NMR studies were carried out on various equimolar mixtures consisting of a combination of oligomers: d(ACGGCT) (I). d(pACGGCT) (Ia), d(TGCAGT) (II), d(AGCCGTACTGCA) (III), d(TGCAGTACGGCT) (IV). It is shown that I + II + III (MI) and Ia + II + III (M2) form stable duplexes with nicks in the centre of the respective double helices. A close analysis of the NOESY experiments of M1 and M2 revealed that these fragments form B-DNA type duplex structures. A comparison of the chemical-shift data of the nicked duplexes with those of the intact duplex of III + IV (M3) demonstrated that only small local distortions occur when a nick is introduced. The chemical-shift profiles of M1 and M3 were used to obtain the thermodynamic data for the duplex/coil transitions. The profiles of M1 were analysed by means of a new thermodynamic model (TRIDUP). From the calculated thermodynamic data of M1 and M3 it is concluded that the melting behaviour of M1 occurs cooperatively. A ligation experiment demonstrated that the relatively small substrate (M2) was almost completely joined after an overnight incubation at 14 degrees C.
对由以下寡聚物组合构成的各种等摩尔混合物进行了核磁共振（NMR）研究：d(ACGGCT)（I）、d(pACGGCT)（Ia）、d(TGCAGT)（II）、d(AGCCGTACTGCA)（III）、d(TGCAGTACGGCT)（IV）。结果表明，I + II + III（MI）和Ia + II + III（M2）在各自双螺旋中心形成带有切口的稳定双链体。对M1和M2的核欧沃豪斯效应光谱（NOESY）实验进行仔细分析后发现，这些片段形成了B-DNA型双链结构。将有切口双链体的化学位移数据与III + IV完整双链体（M3）的化学位移数据进行比较表明，引入切口时仅发生小的局部扭曲。利用M1和M3的化学位移图谱获得双链体/单链卷曲转变的热力学数据。通过一种新的热力学模型（TRIDUP）对M1的图谱进行分析。根据M1和M3计算得到的热力学数据得出结论，M1的解链行为是协同发生的。连接实验表明，相对较小的底物（M2）在14℃下孵育过夜后几乎完全连接。
