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Differential solvation and tautomer stability of a model base pair within the minor and major grooves of DNA

F.-Y. Dupradeau, D.A. Case, C. Yu, R. Jimenez, F.E. Romesberg, J. Am. Chem. Soc. (2005) 127:15612-15617.
pubpic2005dupradeauWe show that when HBO is positioned in the minor groove of DNA, the enol tautomer of HBO is preferentially stabilized, whereas our previous study showed that when HBO is positioned in the major groove, the keto tautomer is preferentially stabilized. Based on MD simulations, we suggest that this results from the formation of a stable hydrogen-bond between the HBO enol and an H-bond acceptor that is only available in the minor groove.

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Femtosecond fluorescence upconversion studies of excited-state proton-transfer dynamics in 2-(2 ‘-hydroxyphenyl)benzoxazole (HBO) in liquid solution and DNA

H. Wang, H. Zhang, O.K. Abou-Zied, C. Yu, F.E. Romesberg, M. Glasbeek, Chem. Phys. Lett. (2003) 367:599–608.
pubpic200wangWe find that the typical time for the excited-state intramolecular proton-transfer reaction of the syn-enol tautomer in solution and in DNA is 150 fs. Picosecond rise and decay components in the fluorescence transients with characteristic times between 3 and 25 ps are observed and attributed to the effects of vibrational cooling.

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Tautomerization dynamics of a model base pair in DNA

O.K. Abou-Zied, R. Jimenez, F.E. Romesberg, J. Am. Chem. Soc. (Comm.) (2001) 123:4613–4614.
pubpic2001abouziedHBO was synthesized and incorporated into DNA oligonucleotides and each oligonucleotide was hybridized to a complementary oligonucleotide containing an abasic site at the position opposite HBO. Analysis of steady state emission spectra of the oligonucleotides indicates that the DNA environment selectively stabilizes the proton-transfer product tautomer of HBO, suggesting that flanking bases may be strongly coupled electronically.

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A phototautomerizable model DNA base pair

A.K. Ogawa, O.K. Abou-Zied, V. Tsui, R. Jimenez, D.A. Case, F.E. Romesberg, J. Am. Chem. Soc. (2000) 122:9917–9920.
pubpic2000ogawa2-(2‘-Hydroxyphenyl)benzoxazole (HBO) undergoes rapid photoinduced proton transfer from the enol-imine to the keto-amine tautomer. When incorporated in duplex DNA opposite an abasic site, HBO appears to be a good mimic of a natural DNA base pair based on duplex stability, UV and CD spectroscopy, and molecular dynamics simulations.