Magnesium protein-based enzymes

If a magnesium cation is incorporated into the active site of a protein-based enzyme, it usually binds via an inner-sphere mechanism in which one or more water ligands in [Mg(OH2)e] are exchanged for organic ligands originating from side chains. The... 

Potassium appears to perform many of the same functions inside the cell that sodium performs in the plasma and interstitial fluid. Potassium, in various ways 1) regulates the maintenance of the osmotic equilibrium of body fluids 2) acts as an available base to neutralize acids 3) maintains an ionic balance between potassium, sodium, calcium, and magnesium, which in turn affects capillary and cell functions and the excitability of nerves and muscles 4) maintains correct water balance in the body and 5) acts as a cofactor in several enzyme systems, including those used for energy transfer and utilization, protein synthesis, and carbohydrate metabolism (Oberleas et al. 

Recent high-resolution crystal structures of the wild-type E. coli enzyme and its complex with phosphate have enhanced our initial understanding of the enzyme mechanism, which was based on earlier lower-resolution structures of the same forms plus the E-P form of the cadmium-substituted enzyme. In all cases, the zinc ions are separated by about 4.0 A, and there are no protein ligands bridging the two zincs. The magnesium ion is located 4.8 A from the less solvent-exposed zinc (Zn2), to which it is linked by a bridging bidentate aspartate carboxylate, and 7.1 A... 

The antibacterial effect of metal ions and especially silver, copper and zinc ions is well known. Silver and silver ions are used in medicinal treatments ranging from severe burns to Legionnaires Diseases. Silver-based products are also applied in water purification processes. Metal ions achieve their antibacterial effect by two mechanisms First the metal ions influence the electrochemical potential between the internal and external parts of the cell, and second, after penetration of ions into the cell, they compete with other essential ions like magnesium, calcium and potassium and they aggregate with thiol groups of enzymes and proteins. 

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