FREE-ENERGY CONTRIBUTIONS OF G.U AND OTHER TERMINAL MISMATCHES TO HELIX STABILITY
FREE-ENERGY CONTRIBUTIONS OF G.U AND OTHER TERMINAL MISMATCHES TO HELIX STABILITY
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DOI：
10.1021/bi00359a019
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发表时间：
1986-06-03
期刊：
影响因子：
2.9
通讯作者：
TURNER, DH
中科院分区：
文献类型：
--
作者：
FREIER, SM;KIERZEK, R;TURNER, DH
用光谱法测定了7种含有GC四聚体核心和G. cnt.U或其它末端错配的六核糖核苷酸的螺旋形成热力学参数。螺旋形成的自由能进行了比较与那些单独的四聚体核心和那些六聚体与6个沃森-克里克碱基对。在1 M NaCl中，在37 ℃下，C时，末端G·U失配的自由能约等于相应的A·U对的自由能。尽管研究的其他末端错配使螺旋形成增加了-1.0至-1.6千卡/摩尔，但所有错配都不如相应的沃森-克里克对稳定。DELTA.G.degree.37末端G·U错配和G·C对的稳定性增量的比较表明，当堆叠较弱时，G·C对中的额外氢键使双链体形成的有利自由能增加约-1千卡/摩尔。
Thermodynamic parameters of helix formation were measured spectroscopically for seven hexaribonucleotides containing a GC tetramer core and G.cntdot.U or other terminal mismatches. The free energies of helix formation are compared with those for the tetramer core alone and with those for the hexamer with six Watson-Crick base pairs. In 1 M NaCl, at 37.degree. C, the free energy of a terminal G.cntdot.U mismatch is about equal to that of the corresponding A.cntdot.U pair. Although other terminal mismatches studied add between -1.0 and -1.6 kcal/mol to .DELTA.G.degree.37 for helix formation, all are less stable than the corresponding Watson-Crick pairs. Comparisons of the stability increments for terminal G.cntdot.U mismatches and G.cntdot.C pairs suggests when stacking is weak the additional hydrogen bond in the G.cntdot.C pair adds roughly -1 kcal/mol to the favorable free energy of duplex formation.