Nanomechanics of diaminopurine-substituted DNA

2,6-diaminopurine (DAP) is a nucleobase analog of adenine. When incorporated into double-stranded DNA, it forms three hydrogen bonds with thymine. Rare in nature, DAP-substitution alters the physical characteristics of a DNA molecule without sacrificing sequence specificity. Here we show that in addition to stabilizing double-strand hybridization, DAP-substitution also changes the mechanical and conformational properties of dsDNA. Thermal melting experiments reveal that DAP-substitution raises melting temperatures without diminishing sequence-dependent effects.

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