The effect of the simultaneous presence of mono- and divalent cations on the thermodynamics of polyelectrolyte solutions is not fully understood. In physiological conditions, combinations of these ions affect structure formation in biopolymer systems. It is known that divalent counterions form a tight sheath around the polymer backbone, while monovalent ions are distributed in a diffuse cloud. ...

Alkali metal and alkaline earth cations pass readily through the acetylcholine receptor channel. Monovalent cations with larger crystal radii are more permeant than ones with smaller radii. For divalent ions, this selectivity sequence is reversed: smaller ions are more permeant than larger ones. This reversal in selectivity sequence with change of valence from 1 to 2 can be naturally accounted ...

In recent years, numerous computer simulations have been performed on aqueous solutions of monovalent and divalent metal ions. Monte Carlo (MC) and/or Molecular Dynamics (MD) simulations [1] have been reported for example on LiCl [2], NaCl [3], BeCl2 [4], MgCl2 [5], CaCl2 [6] and SrCl2 [7] solutions dealing with the structure of the hydration shell of the ions and spectroscopic data for the ion...

The influence of divalent ions and ADP on the induction, relaxation, and stability of the ADP-induced platelet receptor for fibrinogen was investigated. Platelets, isolated by differential sedimentation and gel filtration in calciumand magnesium-free buffer, exhibited a well defined shape change upon ADP stimulation, but aggregation occurred only when calcium or magnesium were added. ‘“I-Fibrin...

Fructose-1,6-bisphosphatase (Fru-1,6-Pase; D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) requires two divalent metal ions to hydrolyze alpha-D-fructose 1,6-bisphosphate. Although not required for catalysis, monovalent cations modify the enzyme activity; K+ and Tl+ ions are activators, whereas Li+ ions are inhibitors. Their mechanisms of action are still unknown. We report here cr...