Molecular Dynamics in Physiological Solutions: Force Fields, Alkali Metal Ions, and Ionic Strength.
نویسندگان
چکیده
The monovalent ions Na(+) and K(+) and Cl(-) are present in any living organism. The fundamental thermodynamic properties of solutions containing such ions is given as the excess (electro-)chemical potential differences of single ions at finite ionic strength. This quantity is key for many biological processes, including ion permeation in membrane ion channels and DNA-protein interaction. It is given by a chemical contribution, related to the ion activity, and an electric contribution, related to the Galvani potential of the water/air interface. Here we investigate molecular dynamics based predictions of these quantities by using a variety of ion/water force fields commonly used in biological simulation, namely the AMBER (the newly developed), CHARMM, OPLS, Dang95 with TIP3P, and SPC/E water. Comparison with experiment is made with the corresponding values for salts, for which data are available. The calculations based on the newly developed AMBER force field with TIP3P water agrees well with experiment for both KCl and NaCl electrolytes in water solutions, as previously reported. The simulations based on the CHARMM-TIP3P and Dang95-SPC/E force fields agree well for the KCl and NaCl solutions, respectively. The other models are not as accurate. Single cations excess (electro-)chemical potential differences turn out to be similar for all the force fields considered here. In the case of KCl, the calculated electric contribution is consistent with higher level calculations. Instead, such agreement is not found with NaCl. Finally, we found that the calculated activities for single Cl(-) ions turn out to depend clearly on the type of counterion used, with all the force fields investigated. The implications of these findings for biomolecular systems are discussed.
منابع مشابه
Ions at the air/water interface
We present results from theoretical studies of aqueous ionic solvation of alkali halides aimed at developing a microscopic description of structure and dynamics at the interface between air and salt solutions. The traditional view has depicted the air/solution interface of simple electrolytes as being devoid of ions. However, it is now firmly established that polarizable anions, such as the hea...
متن کاملCarboxylate Ion Pairing with Alkali-Metal Ions for β-Lactoglobulin and Its Role on Aggregation and Interfacial Adsorption.
We report a combined experimental and computational study of the whey protein β-lactoglobulin (BLG) in different electrolyte solutions. Vibrational sum-frequency generation (SFG) and ellipsometry were used to investigate the molecular structure of BLG modified air-water interfaces as a function of LiCl, NaCl, and KCl concentrations. Molecular dynamics (MD) simulations and thermodynamic integrat...
متن کاملPolarizable ions at interfaces.
A nonperturbative theory is presented which allows us to calculate the solvation free energy of polarizable ions near water-vapor and water-oil interfaces. The theory predicts that larger halogen anions are adsorbed at the interface, while the alkali metal cations are repelled from it. The density profiles calculated theoretically are similar to those obtained using molecular dynamics simulatio...
متن کاملProperties of alkali-halide salt solutions about polarizable nanoparticle solutes for different ion models.
We investigate the distributions of various salts about large hydrophobic polarizable solutes in aqueous electrolyte solutions. The solutes are modeled as nanometer-sized cylindrical objects, a scale relevant to biomolecules and nanomaterials, and particularly high aspect ratio nanoparticles. Interactions, including image charge forces arising from the finite polarizability of the solute, betwe...
متن کاملStability Constants of Metal Ion Complexes of Cyclopentadienyltris(diethylphosphito-P)cobaltate(l-),
Stabüity Constants, Metal Ion Complexes, Oxygen Tripod Ligand The formation of metal ion complexes ML(> and ML2(>+ of the oxygen tripod ligand L~ = cyclopentadienyltris(diethylphosphito-P)cobaltate(l-) with metal ions M — Li+, Na+, K+, Mg+, Ca+, Sr+, Ba+, Mn+, Co+, Ni+, Cu+, Zn+, Cd+, Hg+, Pb+, Ag+, and La has been studied by pH titration at 25 °C in 95/5 methanol/water solutions kept at an ion...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Journal of chemical theory and computation
دوره 6 7 شماره
صفحات -
تاریخ انتشار 2010