Chemistry and Biology of Non-canonical Nucleic Acids. Naoki Sugimoto

Chemistry and Biology of Non-canonical Nucleic Acids - Naoki Sugimoto


Скачать книгу
Adenine and cytosine also form two hydrogen bonds as similar way as the G·T(U) mismatch when the adenine nucleobase is protonated (Figure 2.2). Formation of the A+·C mismatched base pair is demonstrated by X-ray diffraction analysis using dodecamer oligonucleotide strand [7]. However, neutral A·C mismatches are in equilibrium between the wobble and reverse wobble forms, each of which only forms one hydrogen bond. Thus, A·C mismatch is much less stable than G·T(U) mismatch in a physiological condition (Tables 2.1 and 2.2).

Schematic illustration of the wobble base pairs in duplexes. Chemical structures of G-T (a), G-U (b), and A+-C (c) wobble base pairs. N1 atom of adenine nucleobase is protonated. (d) Structure of B-form DNA duplex containing G-T wobble base pairs. (e) Structure of A-form RNA duplex containing two consecutive G-U wobble base pairs. (f) Structure of B-form DNA duplex containing A+-C wobble base pairs. Nucleobases forming the wobble base pairs are emphasized dark. Hydrogen bonds in the wobble base pairs are shown in dashed lines.

      2.2.3 Purine–Purine Mismatches

−ΔH° −ΔS° −Δupper G 37 Superscript normal o T m
Sequence XY (kcal mol−1) (cal mol−1) K−1) (kcal mol−1) (°C at 10−4 M)
5′CAAA X AAAG CG 64.5 183 7.7 42.9
3′GTTT Y TTTC GC 62.8 179 7.3 40.8
AT 68.0 196 7.2 40.1
TA 58.6 168 6.5 36.8
GG 53.5 158 4.5 25.6
TG 55.6 165 4.4 25.7
GA 52.6 156 4.2 23.9
GT 46.7 137 4.2 22.3
AG 39.9 116 3.9 18.0
AA 36.9 107 3.7 15.0
CT 53.2 161 3.3 19.1
TC 50.0 151 3.2 17.5
CA (120)b) (3.1)Скачать книгу
Librs.Net