Role of metals in enzymatic reactions. Part 2.—Kinetics of complex formation in model systems involving manganese(II) and 8-hydroxyquinoline

Abstract

The temperature-jump relaxation method has been used to measure the kinetics of formation and dissociation of the 1 : 1 complex between manganese(II) and 8-hydroxyquinoline (oxine) and of the ternary complexes between oxine and the manganese(II)-nitrilotriacetate, -uramil NN diacetate, -adenosine-5′-triphosphate and -polytriphosphate complexes. In all cases the data are consistent with a two-path mechanism involving the addition to the manganese species of the oxine anion or the oxine molecule. The first ligand has comparatively little influence on the rate at which manganese reacts with and dissociates from the second ligand. The observed enzymatic behaviour of manganese(II), magnesium and calcium is discussed in the light of the results.