Physicochemical Properties of 3-Mercaptopyruvate Sulfurtransferase: A Cyanide Detoxifying Enzyme from the Hemolymph of Limicolaria flammae (Garden Snail)
Pan African Journal of Life Sciences
3-Mercaptopyruvate sulfurtransferase (3-MST) is a multifunctional, mitochondrial and cytoplasmic sulphurtransferase that catalyses the detoxification of cyanide to a less toxic thiocyanate. Limicolaria flammea feeds majorly on green leaves, plants and other cyanide containing foods. Methods: 3-MST from the hemolymph of Limicolaria flammae was purified by 70 % ammonium sulphate precipitation and ion exchange chromatography. The purified enzyme was characterized at different levels such as
... vels such as optimal activity, inhibitors, substrate preference, thermal stability and analysis of ki-netic parameters. Results: 3-MST from the hemolymph of Limicolaria flammae had a yield of 0.75 % with specific activity of 0.42 μ/mg/ml. The Km values for the substrates; KCN and 2-Mercaptoethanol were 1.09 and 2.83 mM, while the Vmax values were 3.08 μml/mol/min and 6.17 μml/mol/min respectively. The optimum pH and temperature of the enzyme were 5.0 and 60° C respectively. The metals (Al3+, Ca2+, and K+) demonstrated inhibitory activity in a concentration dependent manner. The substrate specificity study showed that sodium sulphite, ammonium per sulphate and ammonium sulphite showed enzymatic interference. Conclusion: This study affirmed the presence of 3-MST activity in the hemolymph of Limicolaria flammea, an indication that the enzyme possesses functional cyanide detoxification mechanism necessary for the survival of the animal in the environment.