Table 2. Average Binding Energies (kcal/mol) of Pairwise Cationic–Aromatic Interactions Involving Hisa.
| CH–πb |
cation–πb |
H-bondsb |
||||
|---|---|---|---|---|---|---|
| solvent | gas phase | solvent | gas phase | solvent | gas phase | |
| His0–Lys | –1.9 ± 0.1 | –8.0 ± 1.5 | –2.0 ± 0.4 | –9.4 ± 2.6 | –6.7 ± 2.6 | –28 ± 8.8 |
| His0–Arg | –3.3 ± 0.1 | –7.8 ± 1.9 | –3.4 ± 0.3 | –8.2 ± 1.2 | –6.3 ± 1.4 | –22 ± 6.6 |
| His0–His+ | –2.4 ± 0.6 | –7.2 ± 2.8 | –3.7 ± 0.6 | –8.5 ± 1.9 | –8.8 ± 1.3 | –26 ± 4.0 |
| His+–Phe | –2.8 ± 0.6 | –7.0 ± 3.3 | –3.9 ± 0.6 | –10 ± 1.4 | ||
| His+–Tyr | –3.4 ± 0.9 | –9.6 ± 3.5 | –4.3 ± 0.6 | –11 ± 1.7 | –4.8 ± 0.2 | –15 ± 0.6 |
| His+–Trp | –3.7 ± 1.3 | –11 ± 4.2 | –5.4 ± 1.0 | –15 ± 2.0 | ||
| Phe–Lys | –2.2 ± 0.2 | –12 ± 1.6 | –2.4 ± 0.4 | –12 ± 3.5 | ||
| Tyr–Lys | –2.3 ± 0.2 | –12 ± 1.6 | –2.3 ± 0.4 | –12 ± 2.7 | –3.9 ± 0.5 | –18 ± 0.6 |
| Trp–Lys | –3.0 ± 0.7 | –15 ± 3.7 | –3.1 ± 0.8 | –16 ± 4.9 | ||
| Phe–Arg | –3.2 ± 0.4 | –8.8 ± 0.8 | –3.4 ± 0.4 | –10 ± 1.5 | ||
| Tyr–Arg | –3.4 ± 0.4 | –9.6 ± 1.2 | –3.7 ± 0.4 | –11 ± 1.3 | –4.0 ± 0.3 | –13 ± 1.5 |
| Trp–Arg | –4.4 ± 0.6 | –12 ± 1.2 | –4.7 ± 0.6 | –15 ± 2.3 | ||
a
Only interactions whose binding energy falls below the −1 kcal/mol threshold are considered.
b
CH–π, cation–π, and H-bonding of pairwise interactions were classified based on their geometrical parameters, as described in Methods.