Document Type : Original Article
Department of Biochemistry and Molecular Biology, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria
Department of Chemical Sciences, Kings University, Odeomu, Osun State, Nigeria
Department of Chemical Sciences, Achievers University, Owo, Nigeria
Introduction: Rodent pests are unique threats to agriculture and food security in many developing countries. Hence, this study investigated some physicochemical properties of partially purified arginase from the stomach of cane rats (Thryonomys swinderianus). This was with a view to understanding the significance of the enzyme in nitrogen metabolism, which could be exploited in the control of rodent pests.
Materials and Methods: Arginase was isolated and subjected to 70% ammonium sulfate (NH4)2SO4 precipitation and dialyzed. The dialysate was further purified using ion-exchange chromatography on CM-Sephadex C-50 matrix.
Results: Apparent Km of the enzyme for L-arginine and Vmax were 54 ± 0.7 mM and 0.057 ± 0.1 μmol/minute/ml, while the optimum pH and temperature obtained for the enzyme were 7 and 70 °C, respectively. NaCl, MnCl2, and HgCl2 activated the enzyme activity, while FeCl3 totally inactivated the enzyme at tested concentrations. β-mercaptoethanol, urea, and EDTA profoundly potentiated the activity of the enzyme. Enzyme activity (81%) was retained when arginine was substituted with cysteine, while histidine, proline, alanine, tyrosine, and tryptophan had potent inhibitory effects on the enzyme activity.
Conclusions: The study established the presence of arginase in the stomach of cane rat and illuminated some physicochemical properties of the enzyme, which could be exploited in its deployment as a viable strategy to control T. swinderianus. However, further studies including structure-function investigations of the enzyme are recommended to fully exploit its potential in the control of rodent pests.