Ribonuclease Activity of Goat Brain Cortex Ribosomal Preparation*

Alkaline Phosphodiesterase Activity of Goat Brain Cortex Ribosomes

“…The observed PDase activity even in the presence of arsenate and zinc ions which are inhibitors of brain cortex PMase activity indicates that the PDase activity of the ribosomal preparation is different from the PMase activity present therein. The differential inhibition of the enzymic activities by the same ions or agents along with the differential heat inactivation (DATTA, BHATTACHARYYA and GHOSH, 1964;DATTA and GHOSH, 1964u) also supports the above view. In the same preparation, urea markedly activates the ribosomal RNase activity (DATTA, BHATTACHARYYA and GHOSH, 1964) but it suppresses drastically the ribosomal PDase activity ( Table 8).…”

“…Attempts to separate and isolate PDase enzyme from the ribosomal particles by ultracentrifugation using sucrose gradients, by electrophoresis using different buffers, or by starch gel electrophoresis or by detergents and salts were unsuccessful in the present study. Similar attempts to separate and isolate RNase from brain cortex ribosomal particles were also unsuccessful in a previous study (DATTA, BHATTACHARYYA and GHOSH, 1964).…”

“…The effect of different concentrations of urea on the ribosomal PDase activity is presented in Table 8, which shows increasing inhibition of the PDase activity with higher concentrations of urea. In this respect the ribosomal PDase was quite different from the ribosomal RNase activity, which was activated about two-fold at PH 5.4 (DATTA, BHATTACHARYYA and GHOSH, 1964). Urea, a hydrogen bond disrupting agent, is likely to dissociate the protein and RNA moieties of the ribosomal particles.…”

“…If it is assumed, in view of the findings of K I~Y (1956), ELSON ( 1 9 5 8~~ 6 ; 1959) and TASHIRO, SHIMIDZU, HONDE and INOUYE (1960), that urea splits the hydrogen bonds holding the protein to the RNA moieties of the ribosomes, thereby releasing the protein moiety and exposing some of its active centres meant for the PDase activity to the inhibitory action of urea at high concentrations, it is tempting to suggest that the active centres of ribosomes for the PDase activity are quite different from those for RNase activity, which are activated by urea (DATTA, BHATTACHARYYA and GHOSH, 1964).…”

“…Estimation of phosphomonoesterase activity. The PMase activity was measured by the principle of BESSEY, LOWRY and BROCK (1946) as described earlier (DATTA and GHOSH, 1964~). In all assays blanks of substrates, reagents and enzymes were run and their values deducted from the test.…”