Question #44960

Consider the rare keto-enol tautomerization of the purine base Guanine ($\ce{G \rightleftharpoons G^*}$) within a deoxyribonucleotide residue in a DNA strand at $298\text{ K}$ and physiological pH. Evaluate the following statements regarding its stereoelectronic properties and structural geometry:

I. In the enol tautomer ($\ce{G^*}$), the N1 atom transitions from a hydrogen bond donor to a hydrogen bond acceptor due to proton migration to the C6 oxygen. II. $\ce{G^*}$ forms a stable mispair with Thymine ($\ce{T}$) because the altered hydrogen-bonding profile perfectly complements the N3-H donor and C4=O acceptor of Thymine. III. The tautomeric shift alters the dipole moment and effective pairing distance, inducing a conformational shift of the $\beta$-N-glycosidic linkage towards the \textit{syn} geometry to alleviate steric hindrance with the sugar-phosphate backbone. IV. The standard Gibbs free energy change ($\Delta G^\circ$) for the $\ce{G \rightleftharpoons G^*}$ transition is highly negative, which drives the spontaneous formation of Z-DNA.

Which of the given statements are correct?