CIRCULAR-DICHROISM MEASUREMENTS SHOW THAT C.C+ BASE-PAIRS CAN COEXIST WITH A.T BASE-PAIRS BETWEEN ANTIPARALLEL STRANDS OF AN OLIGODEOXYNUCLEOTIDE DOUBLE-HELIX
CIRCULAR-DICHROISM MEASUREMENTS SHOW THAT C.C+ BASE-PAIRS CAN COEXIST WITH A.T BASE-PAIRS BETWEEN ANTIPARALLEL STRANDS OF AN OLIGODEOXYNUCLEOTIDE DOUBLE-HELIX
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DOI：
10.1093/nar/12.19.7565
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发表时间：
1984-01-01
影响因子：
14.9
通讯作者：
RATLIFF, RL
中科院分区：
文献类型：
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作者：
GRAY, DM;CUI, T;RATLIFF, RL
我们研究了DNA寡聚体d（C_4A_4T_4C_4）的卷曲-螺旋转变，用圆二色性测量监测了中心自互补区A·T碱基对的形成和寡聚体末端质子化C·C ~+碱基对的形成。我们发现，随着温度和pH的降低，A·T和C·C+碱基对以协调的方式形成。寡聚体螺旋形式的CD数据与配对寡聚体的存在一致，但与发夹环不一致。寡聚体C4端之间C·C+碱基对形成的pKa值高于d（C8）端C·C+碱基对形成的pKa值，表明寡聚体中C·C+碱基对的形成受到成对A4 T4区的影响。我们的结论是，A·T和C·C+碱基对共存于寡聚体的自身复合物中，因此，C·C+碱基对可以在反平行DNA链之间形成。
We have studied the coil-to-helix transition of the DNA oligomer d(C4A4T4C4), using circular dichroism measurements to monitor the formation of A.T base pairs within the central self-complementary A4T4region and the formation of protonated C·C+base pairs at the ends of the oligomer. We found that both A·T and C·C+base pairs formed in a coordinated fashion as the temperature and pH were lowered. The CD data of the helix form of the oligomer were consistent with the presence of paired oligomers, but not with hairpin loops. The pKa for formation of C·C+base pairs between the C4 ends of the oligomer was higher than the pKa for formation of C·C+base pairs in d(C8), indicating that the formation of C·C+base pairs in the oligomer was Influenced by the presence of a paired A4T4region. We conclude that A·T and C·C+base pairs coexist in the self-complex of the oligomer and, therefore, that C·C+base pairs can form between antiparallel DNA strands.