期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1975
卷号：72
期号：6
页码：2049-2053
DOI：10.1073/pnas.72.6.2049
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The high resolution nuclear magnetic resonance (NMR) spectra of hydrogen-bonded protons in four tRNAs have been studied at 270 MHz. The relative intensity of the resonances between -11 ppm and -15 ppm of Escherichia coli tRNA1Val indicate that there are 26 {+/-} 3 protons, while only 20 are expected from secondary structure Watson-Crick hydrogen bonds in the cloverleaf structure. Several possible candidates for these extra resonances are suggested by tertiary interactions observed in recent crystallographic studies. Of the four tRNAs studied, three, e.g., E. coli tRNA1Val, E. coli tRNAArg and E. coli tRNAPhe have one "GU pair" in their cloverleaf structure, while the fourth, yeast tRNAAsp, has three "GU pairs" and one "G{Psi} pair". Correlating these with the NMR spectra in the -10 ppm to -11 ppm region allows us to conclude that the "GU pairs" are not hydrogen-bonded by tautomerization to the lactim form. At the very low field region, near -14.9 ppm, the three E. coli tRNAs show a single resonance which is attributed to the 4-thiouracil 8 to adenine 14 hydrogen bond of the tertiary structure, by analogy with the recent crystal structure of yeast tRNAPhe. This assignment is confirmed by the disappearance of this resonance after treatment with cyanogen bromide.
关键词：base pairing ; high resolution nuclear magnetic resonance
