Characterization of cytosine deaminase with substrate specificity to 5-fluorocytosine

5-fluorocytosine에 기질특이성을 가지는 cytosine deaminase의 특성

A cytosine deaminase from the cell-free extract of an isolate was examined after ethyl alcohol reactionation. The enzyme catalyzed the conversion of 5-fluorocytosine to 5-fluorouracil by the possession of specificity to the substrate. The optimum temperature and storage time on the stability of the enzyme were at below $50^{\circ}C$ and near 2 days in tris-HCl buffer. The maximum activity was also presented ar 9.0 in pH and $45^{\circ}C$ in temperature. The pHs and temperatures for the enzyme activity ranged from 8.5-9.5 and from 40-$50^{\circ}C$, respectively. the presence of $Ag^{+}, Hg^{2+}, Zn^{2+}$ in the reaction mixture resulted in the marked inhibition in the activity, but 1mM of $Fe^{3+}, K^{+}$, or $Na^{+}$ increased the enzyme activity. The enzyme preparation was vot affected by inhibitors used except N-ethylmaleimide of 1 and 10mM, and considerably activated by 1mM of pyrophosphate and 10mM of phosphate.