Table 3. Errors in the Estimated QM/MM Polarization Energy for the Oxyluciferin–Luciferase Complexa.
| 6-31+G*
basis |
|||||
|---|---|---|---|---|---|
| functional | scheme | MSE | RMS | MAX | REL |
| B3LYP | MESS-E | –2.731 | 2.874 | 5.266 | 82.7% |
| MESS-H(120) | 0.251 | 0.254 | 0.341 | 7.9% | |
| MESS-H(180) | 0.174 | 0.176 | 0.237 | 5.5% | |
| MESS-H(240) | 0.136 | 0.137 | 0.190 | 4.3% | |
| M06-2X | MESS-E | –1.114 | 1.169 | 2.129 | 35.2% |
| MESS-H(120) | 0.222 | 0.224 | 0.296 | 7.3% | |
| MESS-H(180) | 0.149 | 0.150 | 0.208 | 4.9% | |
| MESS-H(240) | 0.104 | 0.105 | 0.161 | 3.4% | |
| ωB97X-D | MESS-E | –0.558 | 0.605 | 1.219 | 17.6% |
| MESS-H(120) | 0.185 | 0.187 | 0.258 | 6.1% | |
| MESS-H(180) | 0.113 | 0.115 | 0.176 | 3.7% | |
| MESS-H(240) | 0.077 | 0.079 | 0.129 | 2.5% | |
a
The oxyluciferin substrate is the QM region, and the luciferase is described with the CHARMM force field. Mean signed errors (MSE), root mean square errors (RMS), maximum errors (MAX), all in kcal/mol, in the QM/MM polarization energies estimated with MESS-E and MESS-H schemes are listed, together with the average of the relative unsigned error (REL). Averaged over 100 configurations from a 100 ps trajectory.