Competition between protein ligands and cytoplasmic inorganic anions for the metal cation: A DFT/CDM study

Many of the essential metalloproteins are located in the cell, whose cytoplasmic fluid contines several small inorganic anions, such as [Cl.sup.-], [NO2.sup.-], [NO3.sup.-], [H2PO4.sup.-] and [SO4.sup.3-], that play an indispensable role in determining the cell's volume, regulating the cell's pH, signal transduction, muscle contraction and cell growth and metabolism. The physiochemical basis for the competition between these abundant, intracellular anions and protein or nucleic acid residues in binding to cytoplasmic metal cations such as [Na.sup.}, [K.sup.1], [Mg.sup.2} and [Ca.sup.2} is delineated using density functional theory in conjunction with the continuum dielectric method.