Ramstein J, Buckingham R H
Proc Natl Acad Sci U S A. 1981 Mar;78(3):1567-71. doi: 10.1073/pnas.78.3.1567.
Measurements of tritium exchange on tRNA were made for periods from 0.5 min to 8 hr after separation from labeled solvent. The exchange curve was analysed in terms of three kinetic classes of exchanging protons with half-lives of 5 hr (12 protons), 0.54 hr (37 protons) and about 3.5 min (58 protons) at 0 degrees C in 0.14 M K+/10 mM Mg2+. The behaviour under varying ionic conditions of protons in the slowest exchange class and of some protons in the intermediate class suggests that they are dependent on the tertiary structure of the molecule. Moreover, in the same range of exchange times characteristic of these latter protons, about 9 more protons were observed in the case of a mutant form of tRNA Trp, the UGA-suppressor species, than in the wild-type tRNATrp. These two species differ only in base 24 in the dihydrouridine stem. This dynamic difference between the wild-type and suppressor species may be related to a functionally important difference in coupling between the conformation of the molecule and interactions at the anticodon.
在从标记溶剂中分离后的0.5分钟至8小时内，对tRNA上的氚交换进行了测量。在0.14 M K⁺/10 mM Mg²⁺中，于0℃下，根据三类交换质子的动力学对交换曲线进行了分析，其半衰期分别为5小时（12个质子）、0.54小时（37个质子）和约3.5分钟（58个质子）。最慢交换类别的质子以及中间类别中的一些质子在不同离子条件下的行为表明，它们取决于分子的三级结构。此外，在这些后一类质子特有的相同交换时间范围内，与野生型tRNA⁻Trp相比，在tRNA⁻Trp的突变形式（UGA抑制物种）中观察到大约多9个质子。这两个物种仅在二氢尿苷茎中的第24位碱基不同。野生型和抑制物种之间的这种动态差异可能与分子构象和反密码子处相互作用之间耦合的功能重要差异有关。
