4 research outputs found
Is UV-Induced Electron-Driven Proton Transfer Active in a Chemically Modified A鈥 DNA Base Pair?
Is UV-Induced Electron-Driven Proton Transfer Active in a Chemically Modified A路T DNA Base Pair?
Transient
electronic and vibrational absorption spectroscopies
have been used to investigate whether UV-induced electron-driven proton
transfer (EDPT) mechanisms are active in a chemically modified adenine鈥搕hymine
(A路T) DNA base pair. To enhance the fraction of biologically
relevant Watson鈥揅rick (WC) hydrogen-bonding motifs and eliminate
undesired Hoogsteen structures, a chemically modified derivative of
A was synthesized, 8-(<i>tert</i>-butyl)-9-ethyladenine
(8tBA). Equimolar solutions of 8tBA and silyl-protected T nucleosides
in chloroform yield a mixture of WC pairs, reverse WC pairs, and residual
monomers. Unlike previous transient absorption studies of WC guanine鈥揷ytosine
(G路C) pairs, no clear spectroscopic or kinetic evidence was identified
for the participation of EDPT in the excited-state relaxation dynamics
of 8tBA路T pairs, although ultrafast (sub-100 fs) EDPT cannot
be discounted. Monomer-like dynamics are proposed to dominate in 8tBA路T