Molecular Dynamics Simulations of a Hydrated Protein Vectorially Oriented on Polar and Nonpolar Soft Surfaces

We present a collection of molecular dynamics computer simulation studies on a model protein-membrane system, namely a cytochrome c monolayer attached to an organic self-assembled monolayer (SAM). Modifications of the system are explored, including the polarity of the SAM endgroups, the amount of wa...

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Bibliographic Details
Published in:Biophysical journal 2002-12, Vol.83 (6), p.2906-2917
Main Authors: Nordgren, C.E., Tobias, D.J., Klein, M.L., Blasie, J.K.
Format: Article
Language:English
Subjects:
Binding Sites
Cell Membrane - chemistry
Computer Simulation
Crystallography - methods
Cytochrome c Group - chemistry
Electrochemistry - methods
Heme - chemistry
Macromolecular Substances
Membrane Proteins - chemistry
Models, Molecular
Molecules
Protein Binding
Protein Conformation
Protein Structure, Secondary
Proteins
Saccharomyces cerevisiae - chemistry
Solvents - chemistry
Surface Properties
Temperature
Water - chemistry
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Summary:We present a collection of molecular dynamics computer simulation studies on a model protein-membrane system, namely a cytochrome c monolayer attached to an organic self-assembled monolayer (SAM). Modifications of the system are explored, including the polarity of the SAM endgroups, the amount of water present for hydration, and the coordination number of the heme iron atom. Various structural parameters are measured, e.g., the protein radius of gyration and eccentricity, the deviation of the protein backbone from the x-ray crystal structure, the orientation of the protein relative to the SAM surface, and the profile structures of the SAM, protein, and water. The polar SAM appears to interact more strongly with the protein than does the nonpolar SAM. Increased hydration of the system tends to reduce the effects of other parameters. The choice of iron coordination model has a significant effect on the protein structure and the heme orientation. The overall protein structure is largely conserved, except at each end of the sequence and in one loop region. The SAM structure is only perturbed in the region of its direct contact with the protein. Our calculations are in reasonably good agreement with experimental measurements (polarized optical absorption/emission spectroscopy, x-ray interferometry, and neutron interferometry).
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(02)75300-9