SELF-COMPLEMENTARY OLIGORIBONUCLEOTIDES - ADENYLIC ACID-URIDYLIC ACID BLOCK COPOLYMERS
SELF-COMPLEMENTARY OLIGORIBONUCLEOTIDES - ADENYLIC ACID-URIDYLIC ACID BLOCK COPOLYMERS
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DOI：
10.1016/0022-2836(71)90341-x
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发表时间：
1971-01-01
影响因子：
5.6
通讯作者：
DOTY, P
中科院分区：
文献类型：
--
作者：
MARTIN, FH;UHLENBECK, OC;DOTY, P
已经制备了一系列腺苷酸和尿苷酸的封闭寡核苷酸，其形式为（Ap）m（Up）n− 1，其中m和n分别在3至7之间变化。当m <n时，单个寡核苷酸在溶液中形成双分子螺旋复合物，但当m< n时，形成含有一些三链螺旋区域的多链聚集体。紫外光谱、Tm的浓度依赖性、熔融和沉降系数的减色性为这些结论提供了证据。即使在腺苷酸和尿苷酸嵌段之间插入非互补碱基，也没有观察到单链发夹螺旋。对于m= n的浓度和温度依赖性的协会是一致的二聚体单体平衡。Tm的浓度依赖性产生了每碱基对的焓变ΔH 1，从− 6.4 kcal/摩尔（Ap）4（Up）3 U至− 7.6 kcal/（Ap）7（Up）6 U.热解离曲线中点的斜率产生的平均值仅为− 5.5 kcal。摩尔1 Tm与1 N（N= m+ n）的曲线呈线性。然而，必须引入ΔH 1的表观变化，以获得与其他估计值相当的β值。Δ H1的链长依赖性可能来自末端效应和/或腺苷酸序列在不同温度范围内的堆积能的变化，在不同的温度范围内，不同链长的二聚体解离。
A series of block oligonucleotides of adenylic and uridylic acid of the form (Ap) m (Up) n− 1, where m and n vary individually from 3 to 7, have been prepared. Individual oligonucleotides were shown to form bimolecular helical complexes in solution when m⩾ n but when m< n multichain aggregates containing some triple-stranded helical regions form. Ultraviolet spectra, concentration dependence of T m, hypochromicity on melting and sedimentation coefficients provided the evidence for these conclusions. Even with non-complementary bases inserted between the adenylic and uridylic acid blocks no single chain, hairpin helices were observed. For m= n the concentration and temperature dependence of association was consistent with a dimer-monomer equilibrium. The concentration dependence of T m yielded enthalpy changes per base pair, ΔH 1, that increased from− 6.4 kcal./mole for (Ap) 4 (Up) 3 U to− 7.6 kcal./mole for (Ap) 7 (Up) 6 U. The slope of the thermal dissociation curve at midpoint yielded average values of only− 5.5 kcal./mole. Plots of 1 T m, versus, 1 N, where N= m+ n, were linear. However, the apparent variation of ΔH 1 had to be introduced in order to obtain values of β that were comparable to other estimates. The chain-length dependence of ΔH 1 presumably arises from end effects and/or from variations in the stacking energy of the adenylic acid sequences at the different temperature ranges over which different chain-length dimers dissociated.