Table 3.
X-ray crystallographic structural and NBO data for amino acid pairs from the PDB
| Amino acid pair | PDB code | Residues | d1 | d1 | θ 1 | θ 2 | n→π* (kcal mol−1) | Total n→π* (kcal mol−1) | |
|---|---|---|---|---|---|---|---|---|---|
| (Å) | (Å) | (°) | (°) | E 1 (n→π*) | E 2 (n→π*) | E t (n→π*) | |||
| Ile–Pro | 2opc | 135–136 | 2.675 | 2.768 | 75.6 | 71.8 | 1.75 | 0.74 | 2.49 |
| Lys–Pro | 1k3i | 50–51 | 2.975 | 2.938 | 78.9 | 80.5 | 0.44 | 0.38 | 0.82 |
| Cys–Pro | 1gcy | 251–252 | 2.815 | 2.834 | 80.6 | 79.8 | 1.24 | 0.60 | 1.84 |
| Leu–Pro | 1g5a | 379–380 | 2.956 | 2.978 | 80.7 | 79.6 | 0.61 | 0.27 | 0.88 |
| Ile–Pro | 1o7i | 107–108 | 2.986 | 3.082 | 81.6 | 77.8 | 0.44 | 0.19 | 0.63 |
| Val–Pro | 1jnd | 294–295 | 3.119 | 3.135 | 81.6 | 81.1 | 0.17 | 0.10 | 0.27 |
| Ala–Pro | 2xu9 | 264–265 | 2.568 | 2.852 | 83.8 | 72.0 | 3.63 | 0.56 | 4.19 |
| Thr–Pro | 1fj2 | 3–4 | 3.035 | 3.015 | 84.2 | 85.4 | 0.26 | 0.34 | 0.60 |
| Ile–Pro | 1e2w | 208–209 | 3.114 | 3.143 | 84.4 | 83.2 | 0.24 | 0.07 | 0.31 |
| Leu–Pro | 1a2p | 20–21 | 2.904 | 3.007 | 85.3 | 80.5 | 0.72 | 0.33 | 1.05 |
| Pro–Pro | 3cx2 | 186–187 | 2.890 | 2.838 | 86.3 | 88.7 | 0.98 | 0.39 | 1.37 |
| Glu–Pro | 1eu1 | 623–624 | 3.144 | 3.194 | 88.0 | 85.8 | 0.22 | 0.03 | 0.25 |
| Leu–Pro | 2x5o | 141–142 | 2.712 | 2.771 | 88.9 | 86.5 | 1.58 | 1.30 | 2.88 |
| Ala–Pro | 1g12 | 103–104 | 3.108 | 3.152 | 89.3 | 87.3 | 0.32 | 0.10 | 0.42 |
| Pro–Ser | 4psc | 32–33 | 2.998 | 2.946 | 90.4 | 92.4 | 0.46 | 0.33 | 0.79 |
| Thr–Glu | 4pdy | 108–109 | 2.918 | 2.936 | 91.5 | 90.4 | 0.72 | 0.25 | 0.97 |
| His–Ser | 1b6a | 331–332 | 3.128 | 3.108 | 92.3 | 93.2 | 0.13 | 0.14 | 0.27 |
| Ala–Asp | 2bi8 | 95–96 | 2.985 | 2.973 | 92.8 | 93.3 | 0.52 | 0.13 | 0.65 |
| Phe–Pro | 1n08 | 76–77 | 2.943 | 2.941 | 93.2 | 93.3 | 0.52 | 0.10 | 0.62 |
| Leu–Pro | 1eb6 | 110–111 | 3.176 | 3.175 | 93.4 | 93.2 | 0.14 | 0.10 | 0.24 |
| Leu–Tyr | 3u26 | 101–102 | 2.826 | 2.893 | 93.6 | 90.2 | 0.96 | 0.34 | 1.30 |
| Ser–Asp | 3ry4 | 79–80 | 2.952 | 2.981 | 94.2 | 92.9 | 0.56 | 0.12 | 0.68 |
| Ala–Phe | 4y1w | 139–140 | 2.947 | 2.973 | 95.3 | 93.9 | 0.54 | 0.26 | 0.80 |
| Gln–Lys | 3wcq | 9–10 | 2.815 | 2.816 | 95.9 | 96.9 | 1.03 | 0.16 | 1.19 |
| Thr–Thr | 3uxf | 349–350 | 2.987 | 2.975 | 96.4 | 97.3 | 0.28 | 0.13 | 0.42 |
| Ala–Arg | 1ejd | 119–120 | 3.175 | 3.171 | 99.3 | 99.0 | 0.13 | NP | 0.13 |
| Phe–Gly | 1odv | 28–29 | 3.129 | 3.169 | 102.4 | 100.3 | 0.13 | 0.02 | 0.15 |
| Asp–Pro | 2vzp | 2–3 | 3.026 | 3.026 | 103.6 | 103.3 | 0.07 | 0.19 | 0.26 |
| Ala–Leu | 1ikp | 388–389 | 3.141 | 3.183 | 104.5 | 102.4 | 0.12 | NP | 0.12 |
| Ala–Ala | 3s5m | 402–403 | 2.485 | 2.999 | 113.6 | 84.2 | 0.89 | 0.01 | 0.90 |
The calculations were carried out at B3LYP/6-311 + G(2d,p) level of theory. For the definitions of d1, d2, θ 1 and θ 2 see Supplementary Fig. 6. E 1 (n→π*), E 2 (n→π*) and E t (n→π*) have same meaning as described before in Table 1. [CO-I and CO-II are randomly chosen in these molecules]
NP not present