Abstract
Incubating the dried cells ofBrevibacterium sojaeNo.425-40 in alkaline buffer, the excretion of 5'-nucleotides accompanying with the decrease of intracellular RNA was observed. Then the determination of the optimum condition of the excretion and the investigation on the enzyme responsible for the degradation of endogenous RNA were carried out.
In the experiments using sonicate and disrupted cells, it appeared that orthophosphate and Mg++might be accelerative or essential for the degradation of endogenous RNA and, in addition to four 5'-nucleotides (AMP, GMP, UMP and CMP), each nucleoside 5'-diphosphate was also contained in its degraded products. Nucleoside 2'- or 3'-monophosphates were not detected. Although it was not clear whether phosphodiesterase concerned with the degradation of intracellular RNA or not, it was suggested that polynucleotide phosphorylase acted mainly on the degradation.
The maximal excretion of 5'-nucleotides from dried cells was obtained by suspending 1 to 2% of dried cells in 0.05M carbonate-bicarbonate buffer (pH 10) and incubating it at 60°C for two to three hours. Orthophosphate and Mg++were not required for the excretion.
