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A Combined Atomic Force Microscopy and Molecular Dynamics Simulation Study on a Plastocyanin Mutant Chemisorbed on a Gold Surface
Author(s) -
Bizzarri Anna Rita,
Bonanni Beatrice,
Costantini Giulio,
Cannistraro Salvatore
Publication year - 2003
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200300792
Subject(s) - plastocyanin , molecular dynamics , chemistry , substrate (aquarium) , crystallography , covalent bond , chemical physics , adsorption , molecule , colloidal gold , nanotechnology , computational chemistry , materials science , nanoparticle , organic chemistry , biochemistry , photosystem i , oceanography , chloroplast , gene , geology
A mutant of copper plastocyanin, covalently bound to an Au (111) surface through an engineered disulfide bridge, was investigated in aqueous medium by atomic force microscopy (AFM) and molecular dynamics (MD) simulations. Tapping‐mode AFM images revealed adsorption of single molecules which are homogeneously distributed over the substrate and strongly bound to gold and display uniform lateral size. A statistical analysis of the height of the macromolecules on the gold substrate evidenced a distribution around a mean value consistent with that expected from the crystallographic data and with a relatively large standard deviation. A 10‐ns classical MD simulation of mutated plastocyanin, hydrated by a layer of water, covalently bound to a gold surface by one or two sulfur atoms, was performed. The simulations indicate that the bound protein retains, in both cases, its overall tertiary structure during the dynamic evolution. Moreover, the macromolecule can assume different orientations with respect to the gold substrate, which give rise to a distribution of heights on the gold substrate. Experimental and MD simulation results are compared and discussed in connection with the topological and dynamical properties of the protein system.