Phosphate-transfer reactions by nuclei from rat thymus gland

‘Glucose 6-Phosphate-Dehydrogenase’ Activity and Thiol Content of Thymus Nuclei From Control and X-Irradiated Rats

“…These results showed that the dehydrogenase was fairly readily extracted from nuclei prepared in ionic medium. The decrease in enzyme activity found after resuspension of the nuclei may explain the decreased phosphorylation found in twice-washed nuclei prepared in ionic medium (Ord & Stocken, 1962a).…”

“…In the presence of 1 mM-GSSG the formation of pyrophosphate was diminished to about 30 % of that in the control nuclei (Table 9). DISCUSSION Ord & Stocken (1961, 1962a showed that nuclei prepared in ionic medium took part in both phosphate transfer reactions and in the activation of amino acids. From the results reported above it is clear that marked loss of protein from the nucleus occurs in this type of preparation (see also Allfrey, 1959) and this presumably accounts for the variability in glucose 6-phosphate-dehydrogenase concentrations in these 'nuclei.…”

“…Creasey & Stocken (1959) showed that the formation of acid-labile phosphate by nuclei isolated from rat thymus gland was completely prevented by exposing the animals to a 100 r. dose of X-rays. The possible function of 'glucose 6phosphate dehydrogenase' (EC 1.1.1.49) in this nuclear phosphorylation (Ord & Stocken, 1962a) led to an examination of the activity of the enzyme after irradiation. The results suggested that alterations in the concentration of thiol (SH) compounds in the nuclei from normal rats might influence the activity of the dehydrogenase and that such alterations might be produced by X-irradiation.…”

The effects of 200r. of x-radiation in vivo on phosphate-transfer reactions in nuclei from rat thymus gland

“…It was considered that this gave evidence for phosphorylation by the isolated nuclei. When rats were exposed to 200r., and the nuclei isolated in a similar way, no increase in pyrophosphate was found (Table 1), although the initial preparation contained more pyrophosphate than did 'fresh' nuclei from control rats (Ord & Stocken, 1962). The concentration of arginine also resembled that in 'aged' nuclei from normal rats.…”

“…given either in vivo or in vitro. With the elucidation of some of the factors involved in the phosphorylation (Ord & Stocken, 1962) it was decided to re-examine the radiosensitivity in an attempt to pin-point the lesion more precisely.…”