Characterizing Partially Purified Rhodanese Enzyme From The West African Mud Creeper
Dokubo A
Department of Biochemistry, Rivers State University, Port Harcourt, Nigeria
Igwe F U
Department of Biochemistry, Rivers State University, Port Harcourt, Nigeria
Nwaokezi C O
Department of Biochemistry, Rivers State University, Port Harcourt, Nigeria
Okwakpam F N
Department of Biochemistry, Rivers State University, Port Harcourt, Nigeria
Keywords: Rhodanese, cyanide detoxification, enzyme, Tympanotonos, fuscatus, environment
Abstract
Indiscriminate release and deposition of hazardous substances continue to produce streams of pollutants into the environment. Research efforts geared towards the development of new low-cost and eco-friendly agents capable of reducing, detoxifying and eliminating pollutants are ongoing. Certain enzymes, extracted from natural sources, have shown great promise in restoring polluted environment due to their enormous ability to transform and detoxify wide range of pollutants. This study was conducted to characterize partially purified rhodanese, a known cyanide detoxifying enzyme, from the West African mud creeper (Tympanaotonos fuscatus) or periwinkle. The enzyme was partially purified using ammonium sulphate [(NH4)2SO4] precipitation and gel filtration chromatography and some of its specific biochemical characteristics assessed using standard methods. Results showed a yield of 2.58 U/mg protein and 4.42 U/mg protein for the (NH4)2SO4 precipitation and gel filtration chromatography respectively. The purification efficiency from gel filtration chromatography was observed to be approximately twice that obtained for the (NH4)2SO4 precipitation. The kinetic parameters evaluated showed that the Km for KCN and Na2S2O3 were 39.76mM and 18.37mM respectively while the Vmax were 1.67µM/min and 2.10µM/min respectively. Substrate specificity study showed that the enzyme exhibited high affinity for sodium thiosulphate (100%), sodium metabisulphite (76%) and 2-mercaptoethanol (47%). The optimum pH was in the range of 8-10 while the optimum temperature was 50oC. The enzyme was most stable at 30oC, its activity was inhibited at the different concentrations of metal ions and the estimated molecular weight was found to be 39,700 Dalton. This study demonstrated that the biochemical characteristics of rhodanese extracted from periwinkle is comparable to the activities of rhodanese from other organisms and tissues. The rhodanese enzyme from this organism may be exploited as eco-friendly agent for extreme cyanide detoxification and bioremediation.