Table 1. Average Binding Energies (kcal/mol) of Pairwise Aromatic–Aromatic Interactions Involving Hisa.
| CH–πb |
stackedb |
H-bondsb |
||||
|---|---|---|---|---|---|---|
| solvent | gas phase | solvent | gas phase | solvent | gas phase | |
| His0–His0 | –2.4 ± 0.3 | –2.7 ± 0.8 | –3.0 ± 0.2 | –3.3 ± 1.1 | –5.7 ± 0.9 | –9.4 ± 1.4 |
| (–3.9 ± 0.5)c | (–8.3 ± 1.9)c | |||||
| (–2.6 ± 0.4)d | ||||||
| His0–Phe | –2.7 ± 0.3 | –3.4 ± 0.6 | –3.1 ± 0.4 | –3.5 ± 0.9 | ||
| (–4.1 ± 0.5)e | (–9.6 ± 1.2)e | |||||
| His0–Tyr | –3.0 ± 0.3 | –3.7 ± 0.8 | –3.2 ± 0.3 | –3.9 ± 0.8 | –6.4 ± 2.4 | –8.9 ± 2.9 |
| (–4.5 ± 0.5)e | (–10 ± 1.4)e | |||||
| His0–Trp | –3.2 ± 0.8 | –3.9 ± 1.5 | –4.0 ± 0.4 | –4.9 ± 1.0 | –5.4 ± 0.8 | –8.8 ± 1.5 |
| (–5.6 ± 0.7)e | (–14 ± 2.4)e | |||||
| Phe–Phe | –2.9 ± 0.3 | –3.4 ± 0.4 | –3.3 ± 0.3 | –3.7 ± 0.5 | ||
| Phe–Tyr | –3.1 ± 0.3 | –3.7 ± 0.5 | –3.5 ± 0.3 | –4.0 ± 0.7 | ||
| Phe–Trp | –3.4 ± 0.6 | –4.2 ± 0.9 | –4.2 ± 0.5 | –4.7 ± 0.5 | ||
| Tyr–Tyr | –3.4 ± 0.4 | –4.1 ± 0.8 | –3.7 ± 0.3 | –4.3 ± 0.6 | –4.8 ± 0.3 | –6.5 ± 0.4 |
| Tyr–Trp | –3.7 ± 0.6 | –4.5 ± 1.1 | –4.4 ± 0.6 | –5.0 ± 0.8 | –4.4 ± 0.5 | –6.6 ± 0.4 |
| Trp–Trp | –4.2 ± 0.6 | –5.0 ± 1.1 | –5.2 ± 0.43 | –5.3 ± 0.7 | ||
a
Only interactions whose binding energy falls below the −1 kcal/mol threshold are considered.
b
CH–π, stacked, and H-bonding pairwise interactions were classified based on their geometrical parameters, as described in Methods.
c
Values refer to the interaction between His0 and His+.
d
Values refer to the interaction between His+ and His+.
e
Values refer to the interaction between His+ and the corresponding aromatic residue.