Guanosine Deaminase Research Articles

細菌によるグアノシンの分解について(第2報)

The authors previously reported that Pseudomonas convexa No. 149 seemed to produce a new enzyme, guanosine deaminase which directly deaminates guanosine producing xanthosine. In this paper, studies were made on several culture conditions for the production of guanosine deaminase. Addition of purine and pyrimidine nucleosides except thymidine to the cultured media, repressed the production of guanosine deaminase. No repression, however, occurred by the addition of purine and pyrimidine bases. This enzyme was produced at stationary phase and no activity was found in the supernatant of broth. Xanthosine formed by the deamination of guanosine with the enzyme was crystallized and identified by the infra-red absorption spectrum.

Studies on the Guanosine Degrading System in Bacterial Cell

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 Hg2+ 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 × 105 to 2 × 105.

Guanine and guanosine deaminase activity of rat mammary gland homogenates through pregnancy and lactation.

SummaryGuanine deaminase activity and guanosine deaminase activity of rat mammary homogenates were studied through pregnancy, lactation and involution. Guanine and guanosine deamination occurred in mammary gland homogenates during all physiological states studied. The rate of deamination of guanine and guanosine exhibited a marked drop from the level of pregnancy to a lower level throughout lactation.

Adenine and adenosine deaminase activity of rat mammary gland homogenates through pregnancy and lactation.

SummaryGuanine deaminase activity and guanosine deaminase activity of rat mammary homogenates were studied through pregnancy, lactation and involution. Guanine and guanosine deamination occurred in mammary gland homogenates during all physiological states studied. The rate of deamination of guanine and guanosine exhibited a marked drop from the level of pregnancy to a lower level throughout lactation.