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Force‐Field Development and Molecular Dynamics Simulations of Ferrocene–Peptide Conjugates as a Scaffold for Hydrogenase Mimics
Author(s) -
de Hatten Xavier,
Cournia Zoe,
Huc Ivan,
Smith Jeremy C.,
MetzlerNolte Nils
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200700358
Subject(s) - molecular dynamics , intramolecular force , force field (fiction) , ferrocene , chemistry , hydrogenase , computational chemistry , chemical physics , crystallography , alanine , amino acid , stereochemistry , physics , electrochemistry , organic chemistry , hydrogen , quantum mechanics , biochemistry , electrode
The increasing importance of hydrogenase enzymes in the new energy research field has led us to examine the structure and dynamics of potential hydrogenase mimics, based on a ferrocene–peptide scaffold, using molecular dynamics (MD) simulations. To enable this MD study, a molecular mechanics force field for ferrocene‐bearing peptides was developed and implemented in the CHARMM simulation package, thus extending the usefulness of the package into peptide–bioorganometallic chemistry. Using the automated frequency‐matching method (AFMM), optimized intramolecular force‐field parameters were generated through quantum chemical reference normal modes. The partial charges for ferrocene were derived by fitting point charges to quantum‐chemically computed electrostatic potentials. The force field was tested against experimental X‐ray crystal structures of dipeptide derivatives of ferrocene‐1,1′‐dicarboxylic acid. The calculations reproduce accurately the molecular geometries, including the characteristic C 2 ‐symmetrical intramolecular hydrogen‐bonding pattern, that were stable over 0.1 μs MD simulations. The crystal packing properties of ferrocene‐1‐( D )alanine‐( D )proline‐1′‐( D )alanine‐( D )proline were also accurately reproduced. The lattice parameters of this crystal were conserved during a 0.1 μs MD simulation and match the experimental values almost exactly. Simulations of the peptides in dichloromethane are also in good agreement with experimental NMR and circular dichroism (CD) data in solution. The developed force field was used to perform MD simulations on novel, as yet unsynthesized peptide fragments that surround the active site of [Ni–Fe] hydrogenase. The results of this simulation lead us to propose an improved design for synthetic peptide‐based hydrogenase models. The presented MD simulation results of metallocenes thereby provide a convincing validation of our proposal to use ferrocene–peptides as minimal enzyme mimics.