Role of Metals in Enzymatic Reactions: Part 5. Kinetics of Ternary Complex Formation Between Magnesium and Manganese(II) Species and 8-Hydroxyquinoline

Abstract

The temperature-jump relaxation method has been used to measure the activation parameters for the formation and dissociation of the 1 : 1 complexes between magnesium and manganese(Il) and 8-hydroxyquinoline (oxine) and of the ternary complexes between oxine and the magnesium and mangancse(II) complexes of nitrilotriacetate, uramil-NN-diacctate, adcnosine-5'-diphosphatc, adcnosinc-5 -triphosphate and polytriphosphatc. The results strengthen the previous conclusion that the first ligand has comparatively little influence on the kinetics of the reaction of magnesium with a second ligand,whereas manganese(II) shows similarities to zinc in the reactivity of its complexes. I he enzymatic behaviour of magnesium and mangancsc(ll) is discussed in the light of these results.