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BP: Fachverband Biologische Physik

BP 19: Posters - Computational Biophysics

BP 19.13: Poster

Dienstag, 21. März 2017, 14:00–16:00, P1A

Interactions of polyatomic anions with proteins depend strongly on sodium — Sadra Kashefolgheta and •Ana Vila Verde — MPIKG, Theory and Bio-Systems Dept., Am Mühlenberg 1 OT Golm, 14476 Potsdam, Germany

Polyatomic ions such as sulfates, phosphates or sulfonates are key players in biological processes but the molecular mechanisms by which these ions act are currently incompletely understood. We use molecular simulations and classical, atomistic models with fixed-charge and explicit solvent representation to clarify the molecular mechanisms of interaction between cationic amino acids and sulfates, phosphates and sulfonates, in their methylated and non-methylated forms and in the presence of excess counterions. This works goes beyond prior reports on the topic in that it uses a newly developed, internally consistent force field for all ions, which correctly captures the energy magnitude and length scale of anion-cation interactions. Our results suggest a possible molecular origin of previously unexplained experimental observations: anions that, according to experiment, differ strongly in the magnitude of their interaction with cationic amino acids have in fact very similar interactions with those amino acids, but different interactions with sodium; the presence of excess sodium in the experiments thus determines the experimental outcome due to competition with the cationic sites on the protein.