Theoretical modeling of the heme group with a hybrid QM/MM method

✍ Scribed by Mar�chal, Jean-Didier; Barea, Guada; Maseras, Feliu; Lled�s, Agust�; Mouawad, Liliane; P�rahia, David

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 439 KB
• Volume: 21
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/(sici)1096-987x(200003)21:4<282::aid-jcc4>3.0.co;2-l

✦ Synopsis

The quality of the results obtained in calculations with the hybrid QM/MM method IMOMM on systems where the heme group is partitioned in QM and MM regions is evaluated through the performance of calculations on the 4-coordinate [Fe(P)] (P = porphyrin), the 5-coordinate [Fe(P)(1 -(Me)Im)] (Im = imidazole) and the 6-coordinate [Fe(P)(1 -(Me)Im)(O 2 )] systems. The results are compared with those obtained from much more expensive pure quantum mechanics calculations on model systems. Three different properties are analyzed-namely, the optimized geometries, the binding energies of the axial ligands to the heme group, and the energy cost of the biochemically relevant out-of-plane displacement of the iron atom. Agreement is especially good in the case of optimized geometries and energy cost of out-of-plane displacements, with larger discrepancies in the case of binding energies.