| Abstract | Alkaline phosphatases (AP) are enzymes that hydrolyse compounds containing phosphate groups, specifically, phosphate monoesters, known to work optimally at pH 9.8. This project aimed to investigate whether the activity of calf intestinal AP is affected by a lower pH as it is found in pH 7.0 -8.0, a pH below its optimal pH. A real-time kinetic assay was performed on AP to determine its kinetic activity, using an artificial substrate p-nitrophenyl phosphate (pNPP) which is converted to p-nitrophenyl by AP, and absorbs at 410nm. Firstly, using varying concentrations of AP at fixed pNPP concentration, non-rate limiting concentration of AP was determined. Next using this concentration, kinetic parameters, Vmax and Km, of AP were determined at pH 9.8, 8.5, 8.0 and 7.0 through Lineweaver–Burk plots generated by varying substrate concentration. Our results indicate that the activity of calf intestinal alkaline phosphatase is not affected substantially by pH values between 8.0 and 9.8. However, at pH 7.0, the activity was irregular and disrupted, indicating that pH values below 8.0 inhibit the activity of calf intestinal alkaline phosphatase. Since the pH of the calf intestine is between 7.0 and 8.0, our results indicate that there could be a source of enzyme regulation in vivo that causes calf intestinal alkaline phosphatase to work properly in pH environments found in the calf intestine.
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