Ikuta S, Eritja R, Kaplan B E, Itakura K
Department of Chemistry, Illinois Institute of Technology, Chicago 60616.
Biochemistry. 1987 Sep 8;26(18):5646-50. doi: 10.1021/bi00392a010.
One- and two-dimensional nuclear Overhauser effect experiments demonstrate that a single hydrogen bond between a T imino proton and purine N3 is sufficient to hold the base pair dPu.dT in d(CGPuAATTTCG) by a Watson-Crick fashion rather than a Hoogsteen type. In addition, the dPu.dT base pair is well stacked with neighboring base pairs. The spin-lattice relaxation measurements at 30 and 35 degrees C of two decamers, d(CGPuAATTTCG) and d(CGAAATTTCG), reveal that the elimination of two single hydrogen bonds of dA.dT base pairs (due to the substitution of adenine for purine) in the sequence results in an increase in the overall imino proton exchange rate from 7 to 36 s-1 at the site of mismatch.
一维和二维核Overhauser效应实验表明，胸腺嘧啶亚氨基质子与嘌呤N3之间的单个氢键足以使d（CGPuAATTTCG）中的碱基对dPu.dT以沃森-克里克方式而非Hoogsteen类型结合。此外，dPu.dT碱基对与相邻碱基对堆积良好。对两个十聚体d（CGPuAATTTCG）和d（CGAAATTTCG）在30℃和35℃下的自旋晶格弛豫测量表明，序列中dA.dT碱基对的两个单氢键消除（由于腺嘌呤被嘌呤取代）导致错配位点处总的亚氨基质子交换率从7 s-1增加到36 s-1。
