Extended Zinc AMBER Force Field (EZAFF).

Area of Science:

• Computational Chemistry
• Biochemistry
• Materials Science

Background:

• Accurate molecular simulations require reliable force fields for metal ions.
• Existing zinc force fields like ZAFF are limited to specific coordination numbers.
• Zinc's diverse coordination chemistry presents challenges for computational modeling.

Purpose of the Study:

• To develop an extended zinc AMBER force field (EZAFF) capable of handling various zinc coordination states.
• To validate the EZAFF model against experimental and quantum mechanical data for diverse zinc-containing systems.
• To benchmark EZAFF against other molecular mechanics and semiempirical quantum mechanical methods for zinc simulations.

Main Methods:

• Development of the extended zinc AMBER force field (EZAFF) model.
• Parameterization of bonds and angles involving zinc for EZAFF.
• Testing EZAFF on six metalloproteins and six organometallic compounds.
• Comparative benchmarking against Seminario, Z-matrix, HFE, IOD, CM, 12-6-4, AM1, PM3, PM6, and SCC-DFTB models.

Main Results:

• The EZAFF model demonstrated reliability in simulating various zinc coordination spheres.
• EZAFF accurately reproduced molecular geometries and relative energies for tested zinc complexes.
• Semiempirical quantum mechanical methods showed only marginal improvements in accuracy over molecular mechanics models for zinc systems, despite higher computational costs.

Conclusions:

• The EZAFF model provides a robust and efficient approach for simulating zinc in diverse chemical environments.
• Molecular mechanics models, particularly EZAFF, are effective alternatives to computationally intensive quantum methods for studying zinc-containing systems.
• The findings support the broader application of EZAFF in computational studies of metalloproteins and organometallic chemistry.