Abstract

R. O. Arise1, F. F. Davies2 and S. O. Malomo

It is a known fact that alkaline phosphatase (ALP) is a metalloenzyme that requires zinc ion (Zn2+) and magnesium ion (Mg2+) for activity. Cobalt ion (Co2+) however has also been reported to stimulate its activity. The concentration-dependent effects of Mg2+ and Co2+ on rat kidney ALP activity was carried out over a range of 3.33 – 25.67 mM para-nitrophenyl phosphate (p-NPP) concentrations. The investigation showed that Mg2+ and Co2+ are activators of rat kidney ALP. Independent and interactive effects of Mg 2+ and Co 2+ on rat kidney ALP showed Co2+ to be a better activator than Mg2+. The activity of rat kidney ALP was not significantly affected (P < 0.05) by 4 mM Co 2+ in the presence of 4 mM Mg2+ when compared with ALP activity in the presence of 4 mM Co2+ alone. There was no synergism in the interactive effect of cobalt and magnesium ions on rat kidney ALP activity. The result may be of clinical and diagnostic importance in alkaline phosphatase assay procedure where cobalt ions may be employed as a better cofactor than magnesium ion used originally in the procedure. This will ensure sensitive detection of low ALP activity.