Triple Helices and Alternative H-Bonding Schemes

Crystal structure determinations of di-nucleotides such as Na-A- p-U-bHjO and Na-G p C OHjO has confirmed the existence of Watson-Crick-type base pairing (10.74). Some synthetic oligonucleotides, however, show variations from this idealised arrangement. 

FIGURE 10.57 Double-stranded DNA with added oligonucleotide. 

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