PAN AFRICAN JOURNAL OF LIFE SCIENCES
Volume 4, No. 2, August 2020
Physicochemical Properties of 3-Mercaptopyruvate Sulfurtransferase: A Cyanide Detoxifying Enzyme from the Hemolymph of Limicolaria flammae (Garden Snail)
Adeola F. Ehigie1, Raphael E. Okonji2, Fiyinfoluwa D. Ojeniyi1, Mary O. Jesulade1, Leonard O. Ehigie1*
1Department of Biochemistry, College of Health Sciences, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
2Department of Biochemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.
Background: 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 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.
Keywords: 3-mercaptopyruvate sulfurtransferase, cyanide, detoxification, Limicolaria flammea