Under what conditions does G•C watson-crick DNA base pair acquire all four configurations characteristic for A•T watson-crick DNA base pair?

Surprising Conformers of the Biologically Important A·T DNA Base Pairs: QM/QTAIM Proofs

“…We chose as the object of the investigation of the biologically-important A·T DNA base pairs, in particular–Watson-Crick A·T(WC), reverse Watson-Crick A·T(rWC), Hoogsteen A·T(H) and reverse Hoogsteen A·T(rH) base pairs (Donohue and Trueblood, 1960 ; Haschemeyer and Sobell, 1963 ; Hoogsteen, 1963 ; Tchurikov et al, 1989 ; Liu et al, 1993 ; Parvathy et al, 2002 ; Sühnel, 2002 ; Zagryadskaya et al, 2003 ; Brovarets', 2013a , b ; Alvey et al, 2014 ; Nikolova et al, 2014 ; Yang et al, 2015 ; Poltev et al, 2016 ; Zhou, 2016 ; Sathyamoorthy et al, 2017 ; Szabat and Kierzek, 2017 ; Ye et al, 2017 ).…”

“…Thus, the reverse A·T(rWC) Watson-Crick or so-called Donohue DNA base pair (Donohue and Trueblood, 1960 ), which is formed by the rotation of one of the bases according to the other by 180° around the N1–N3 axis of the Watson-Crick A·T(WC) DNA base pair, has been registered in the bioactive parallel-stranded DNA (Tchurikov et al, 1989 ; Parvathy et al, 2002 ; Brovarets', 2013a , b ; Poltev et al, 2016 ; Szabat and Kierzek, 2017 ; Ye et al, 2017 ).…”

“…The A·T(H) Hoogsteen base pair (Hoogsteen, 1963 ) is formed due to the rotation on 180° of the A DNA base relative to the T DNA base around the C9-N9 axis from the anti (WC) to syn (H) conformation, representing itself alternative DNA conformation that is involved into a number of biologically important processes such as recognition, damage induction, replication and has been actively investigated in the literature (Hoogsteen, 1963 ; Brovarets', 2013a , b ; Alvey et al, 2014 ; Nikolova et al, 2014 ; Yang et al, 2015 ; Zhou, 2016 ; Sathyamoorthy et al, 2017 ). In particular, in the canonical DNA double helix Watson–Crick base pairs exist in a dynamic equilibrium with sparsely populated (~0.02–0.4%) and short-lived (lifetimes ~0.2–2.5 ms) Hoogsteen base pairs (Zhou, 2016 ).…”

The A·T(rWC)/A·T(H)/A·T(rH) ↔ A·T*(rwWC)/A·T*(wH)/A·T*(rwH) mutagenic tautomerizationviasequential proton transfer: a QM/QTAIM study

“…First, the A$T(rWC), A$T(H) and A$T(rH) DNA base pairs have a remarkable biological meaning (see works [62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79] and the bibliography cited therein). Second, as of today, the mutagenic tautomerization of these biologically important pairs has not even mentioned in the literature.…”

Quantum-mechanical survey of the novel conformational and tautomeric transformations of the classical Watson-Crick А·Т(WC), reverse Watson-Crick А·Т(rWC), Hoogsteen А·Т(Н) and reverse Hoogsteen А·Т(rН) DNA base pairs

“…-the (A)N1-N3(T) axis, leading to the formation of the reverse Watson-Crick А•Т(rWC) or so-called Donohue DNA base pair [1], registered in the bioactive parallel-stranded DNA [2]- [9]; -the (A)C9´-N9 axis from the anti-to syn-conformation, representing Hoogsteen A•T(H) base pair [10] involved into a number of biologically important processes such as recognition, damage induction, replication [8]- [20];…”