Wu J J, Marshall A G
Department of Biochemistry, Ohio State University, Columbus 43210.
Biochemistry. 1990 Feb 20;29(7):1722-30. doi: 10.1021/bi00459a009.
The base-pair protons of the common arm duplex fragment of wheat germ (Triticum aestivum) ribosomal 5S RNA have been identified and assigned by means of 500-MHz proton NMR spectroscopy. The two previously reported extra base pairs within the fragment [Li et al. (1987) Biochemistry 26, 1578-1585] are now explained by the presence of two distinct solution structures of the common arm fragment (and its corresponding base-paired segment in intact 5S rRNA). The present conclusions are supported by one- and two-dimensional proton homonuclear Overhauser enhancements in H2O and by temperature variation and Mg2+ titration of the downfield 1H NMR spectrum. The difference between the two conformers is most likely due to difference in helical tightness. Some additional amino proton resonances have also been assigned.
利用500兆赫质子核磁共振光谱法，已对小麦胚芽（普通小麦）核糖体5S RNA共同臂双链体片段的碱基对质子进行了鉴定和归属。该片段中先前报道的两个额外碱基对[Li等人（1987年），《生物化学》26，1578 - 1585]，现在可以通过共同臂片段（及其在完整5S rRNA中相应的碱基配对区段）存在两种不同的溶液结构来解释。目前的结论得到了在H2O中的一维和二维质子同核Overhauser增强以及低场1H NMR光谱的温度变化和Mg2+滴定的支持。两种构象体之间的差异很可能是由于螺旋紧密程度的不同。还归属了一些额外的氨基质子共振信号。
