Studies on the Guanosine Degrading System in Bacterial Cell: Part III. Purification and Properties of Guanosine Deaminase

A highly purified preparation of the enzyme, guanosine deaminase, has been obtained by a four-step purification procedure from the cells of Pseudomonas convexa No. 149. The enzyme deaminates guanosine, deoxyguanosine and 8-azaguanosine, and the deamination of guanosine is inhibited by Hg 2+ and 4-amino-5-imidazole carboxamide ribonucleoside. The enzyme has the optimum pH at pH range from 6.0 to 6.5 and the optimum temperature at 45°C. Metal ions are not required for the enzyme activity. The molecular weight of the enzyme is 1 × 10 5 to 2 × 10 5 .