| Abstract |
Some properties of an extracellular cytosine deaminase produced from Arthrobacter sp. JH-13 were examined after 20-80% of ammonium sulfate fractionation. Among some substrates, this enzyme utilized cytosine and 5-fluorocytosine as a substrate. The optimum pH and temperature for the activity of this enzyme were found to be near 8.0 and 40℃, respectively. The ensyme was more stable in 0.2M of Tris-HCl buffer than 0.2M of potassium phosphate buffer. The enzyme was generally stable below 50℃, but inactivated completely at 70℃. 1mM of Fe^3+, K^+ and Na^+ increased the enzyme activity, but 0.01mM of Co^2+, Cu^2+, Ni^2+, Hg^2+, Ag^2+, Zn^2+, Ba^2+, and Mg^2+ markedly inactivated the enzyme activity. 0.1mM of p-chloromercuribenzoate, trichloroacetic acid, and N-ethylmaleimide completely inhibited the enzyme activity, but 0.1mM of 2-mercaptoethanol slightly increased the enzyme activity. |
