To address this problem, we redesigned the pairing partner of s, instead of y, and developed imidazolin-2-one (z) (Fig.
However, contrary to our expectations, the 4MP substrate was not incorporated opposite 4MP at all, although we found that 4MP has unique dual specificity for pairing with A or G.
The PICS-PICS pair is too large for accommodation in the 10.7-11.0A distance of the DNA duplex, and thus, the large and hydrophobic PICS molecules stack on each other in the pairing, and this unusual stacked structure cannot be recognized by polymerases during primer extension.
In 2003, while considering Kool's Z-F and Q-F pairs, which are hydrophobic isosteres of the natural A-T pair, we found that the shape complementarity of these base pair is still imperfect, and the hydrogen atoms in the center on the pairing surface clash with each other (Fig.
We synthesized the substrate and amidite of Pa, and examined the efficiency and selectivity of the Q -Pa pairing in replication by KF.
(80) To prevent the pairing of the enol form of isoG with T, they replaced T with TS, in which the large 2-sulfur atom clashes with the 2-hydroxy group of the enol form of isoG (Figs.
Therefore, we replaced the 1-nitrogen of s with C-H and removed the 2-amino group, and designed the hydrophobic base, 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds), as a new pairing partner of Pa (Fig.
No single answer automatically emerges to pin down what causes the pairing.
Nonetheless, these results are encouraging for theorists, like Scalapino, who have proposed that pairing results from the way electrons interact with fluctuations in the spins of neighboring copper ions in the crystal lattice.
Mechanisms such as pairing are too simple to account for this behavior, and repulsive interactions between electrons must also be included.