Ionophore-mediated cation translocation in artificial systems. I. A23187-mediated calcium translocation.
The inophore A23187 stimulates the translocation of calcium from an aqueous Hepes buffer into an organic immiscible phase. At saturating calcium concentrations, 2 molecules of ionophore seem to complex each atom of calcium. Consistent with such a stoichiometric behaviour, the apparent ratio of calcium-ionophore association to dissociation rate constants increases as the concentration of ionophore is raised. As a result, at low calcium concentrations, the amount of translocated calcium increases as a power function of A23187 concentration. When allowance is made for such a phenomenon, the relation between calcium translocation and concentration is characterized by usual substrate-receptor binding kinetics.
D000900:Anti-Bacterial Agents; D001464:Barium; D001692:Biological Transport; D002021:Buffers; D000001:Calcimycin; D002118:Calcium; D007700:Kinetics; D008274:Magnesium; D008954:Models, Biological
D000900:Anti-Bacterial Agents; D002021:Buffers; D001464:Barium; D000001:Calcimycin; D008274:Magnesium; D002118:Calcium