Bina-Stein M, Crothers D M, Hilbers C W, Shulman R G
Proc Natl Acad Sci U S A. 1976 Jul;73(7):2216-20. doi: 10.1073/pnas.73.7.2216.
We have examined the 270 MHz nuclear magnetic resonance spectrum and relaxation kinetic behavior of tRNA2Glu (E. coli) in the absence of Mg++, a condition which produces an inactive form of this tRNA. The results show that the denatured form has about five fewer proton resonances in the region from -12 to -15 ppm. Relaxation kinetic measurements reveal that the denatured conformer contains three separately melting helices. The results support a model in which the tertiary structure and dihydrouridine helix characteristic of the native form are unfolded in the denatured state, and are replaced by an altered tertiary structure. The acceptor stem, anticodon, and TpsiC helices are intact in this model for the denatured conformation. The optical changes that accompany melting of the denatured tertiary structure are faster than 10 musec.
我们研究了在不存在Mg++的情况下大肠杆菌tRNA2Glu的270兆赫核磁共振谱和弛豫动力学行为，这种条件会产生该tRNA的无活性形式。结果表明，变性形式在-12至-15 ppm区域的质子共振约少五个。弛豫动力学测量表明，变性构象体包含三个分别解链的螺旋。这些结果支持了一个模型，即天然形式的三级结构和二氢尿嘧啶螺旋在变性状态下展开，并被改变的三级结构所取代。在这个变性构象模型中，受体茎、反密码子和TψC螺旋是完整的。变性三级结构解链时伴随的光学变化快于10微秒。
