Isolation and kinetic properties of soldier termite (Amitermes silvestrianus Light, 1930) rhodanese
Rhodanese, a cyanide detoxifying enzyme, was isolated from soldier termite using ammonium sulphate fractionation, reactive blue affinity chromatography and gel filtration on Sephadex G-150. The enzyme had a specific activity of 7.9 RU per milligram of protein. The Km values of the substrates (KCN and Na2S2O3) were 7.0 mM and 5.3 mM respectively. The results of substrate specificity showed that the enzyme was specific for thiosulphate (S2O3 2-) when compared with other sulphur compounds. The native and subunit molecular weight of the enzyme was found to be 37,154 and 32,210 dalton respectively. The optimum pH and temperature of the enzyme activity were 8.0 and 55 oC respectively. NH4 +, Mn2+, and Ba2+ had about 50 % effect on the activity of the enzyme. However, Hg2+, Zn2+ and Mg2+ inhibited the enzyme considerably (= 20 %). The half-life of the enzyme at 40 oC, 50 oC, 60 oC, 70 oC and 80 oC were found to be 150.7, 60.3, 43.0, 37.7 and 37.0 respectively. © 2010 International Formulae Group. All rights reserved.
Keywords: Soldier termite; rhodanese; detoxification; sulphurtransferase enzyme; cyanide toxicity; insects.
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