Outline 1. Methods new version of the energy model PMF calculations instead of adsorption free energy 2. Model validation PMF for amino acids Proteins 3. Outlook
Methods 1. Protein-metal non-polar interactions (sum of Lennard-Jones potentials) - checked 2. Protein-metal electrostatic interaction 3. Desolvation effects - improved 4. Electrostatic interaction between adsorbed water layer on gold and a protein – implemented (only for proteins)
Desolvation energy E 0 is water adsorption energy per unit area; Now desolvation area is defined by vd. W radius of water molecule+ vd. W radius of protein atoms (i. e. ~6 Angstrom) Adsorption energy in the 2 d layer in the 1 st layer distance from the gold surface OLD R NEW = 6. 0 Å 6. 5 Å 2)-1 0. 13 k. J(mol Å2)-1 = 0. 25 k. J(mol Å = 3. 0 Å 6. 0 Å
PMF and adsorption free energy Configurational space: rotation ( i=1 -3) + translation (x=0 -Dx; y=0 -Dy; z=0 -b); DS=Dx. Dy adsorption free energy: PMF energy
Model validation: amino acids on gold Different conformations: Gln Lys His/His. H
Model validation: BLIP/BLIP-3 His From MD simulations BD simulations: BLIP weakly bound DG ~ 1. 6 k. T BLIP-3 HIS is strongly bound ! 3 His. H DG ~ 38 k. T
Model validation: Fibronectin on the gold surface structure from MD simulations DG ~ 36 k. T Conformation is very important!
BLIP
Electrostatic interaction between adsorbed water and a protein
Outlook 1. Model of electrostatic interaction between adsorbed water and protein – must be improved
Acknowledgements • University of Modena and Reggio Emilia • Elisa Molinari • Francesco Iori • Weizmann Institute of Science - Biochemistry • EML Reasearch • Rebecca Wade • Piter Winn • Bingding Huang • Gideon Schreiber • Dana Reichmann • Ori Cohavi • Weizmann Institute of Science – Nanomaterials • Israel Rubinstein, • Alexander Vaskevich • Ludwig Maximilians University • Kay Gottschalk • Martin Hoefling • INFM-CNR National Research Center S 3 • Stefano Corni • Rosa Di Felice • Arrigo Calzolari • Alessandra Catellani Financial support