Influence of Zn2+ and Mg2+ on Some Kinetic Parameters of Alkaline Phosphatase in Agba River Water

Abstract

The level of alkaline phosphatase (ALP) activity in fresh water body was investigated using filtered and unfiltered Agba River water to  assess the level of contamination and the role of cofactors-containing effluents in the degree of acceptable quality of Agba River water.  Alkaline phosphatase catalyses phosphorous recycling, which is important for zooplankton and phytoplankton growth. The activity of  alkaline phosphatase in water can be used to determine if there is pollution in the water or not. Higher activity of alkaline phosphatase  was observed in unfiltered Agba River when compared to the filtered sample and this may be as a result of pollution by phosphoesters or  due to the presence of both bound and free forms of the enzyme. The influence of increase in concentration of zinc and magnesium  ions on the kinetic parameters (K_m and V_max) of unfiltered and filtered Agba River alkaline phosphatase was also determined. Zn²⁺ had  a higher stimulatory effect (with V_max of 0.50-5.00 nmol/min for unfiltered and 0.43-2.00 nmol/min for filtered sample) on the enzyme  rate of reaction when compared to that of Mg²⁺ (with V_max of 0.63-2.50 nmol/min for unfiltered and 0.22-0.71nmol/min for filtered  sample) as depicted by the increase in V_max as the concentration of Mg²⁺ and Zn²⁺ increased. The Km values decreased as the  concentration of Zn²⁺ and Mg²⁺ increased. The presence of ALP in Agba River may serve as a means by which water pollution, through  phosphorus contaminants like detergents, fertilizers and animal wastes from homes and industries, can be reduced. Also, the presence of  Zn²⁺ and Mg²⁺ in the discharged pollutants may further strengthen the reduction of fresh water contamination by ALP.