27 Guanosine Hydrogen bonds

Lena S, Masiero S, Pieraccini S, Spada GP (2009) Guanosine hydrogen-bonded scaffolds a new way to control the bottom-up realisation of well-defined nanoarchitectures. Chem Eur J... 

Schwalb NK, Temps F (2007) Ultrafast electronic relaxation in guanosine is promoted by hydrogen bonding with cytidine. J Am Chem Soc 129 9272... 

The translation model was refined and developed further in a later article (Lehmann and Kuhn, 1984). It is assumed that in the early stages of evolution, guanosine and cytidine were the most important building blocks for RNA syntheses, as they allow strong base pairing (via three hydrogen bonds). Quantitative considerations lead to an upper limit of about 50 nucleotides for a reasonable chain length. 

FIGURE 28.11 Phenylalanine tRNA from yeast, (a) A schematic drawing showing the sequence of bases. Transfer RNAs usually contain a number of modified bases ( gray circles). One of these is a modified guanosine (G ) in the anticodon. Hydrogen bonds, where present, are shown as dashed lines, (b) The structure of yeast tRNAphe as determined by X-ray crystallography. 

Guanosine 10 make a hydrogen-bonded base pair, but other nucleobase positions are poorly constrained by NMR data (Addess et al, 1997 Laing and Hall, 1996 McCallum and Pardi, 2003). To better characterize the loop structure and nucleotide motions, 2AP replaced A7 and G8 in the IRE (Fig. 13.4). 

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