Stability of DNA duplexes containing hypoxanthine (inosine): gas versus solution phase and biological implications.

A series of 9-mer DNA duplexes of the sequence 5'-d(GGTTXTTGG)-3'/3'-d(CCAAYAACC)-5', where the central base X or Y = adenine (A), guanine (G), thymine (T), cytosine (C), and hypoxanthine (H), have been examined toward understanding the effect of hypoxanthine on DNA stability. Comparison of the duplex stability in the gas phase versus solution indicates that hypoxanthine has much less of a destabilizing effect in the gas phase versus in solution, relative to the normal complementary duplexes. The biological implications of these results, both in the context of hypoxanthine as a universal base and as a damaged base, are discussed.