[Xanthine oxidase activity of thymocytes in lymphocytolytic effect of hypoxanthine]. / Ksantinoksidaznaia aktivnost' timotsitov pri limfotsitoliticheskom deistvii gipoksantina.

Destruction of thymocytes, caused by incubation with hypoxanthine, was decreased distinctly after addition of allopurinol as shown by eosin staining. Lymphocytolytic effect of hypoxanthine was accompanied by considerable activation in thymocytes of endogenous xanthine oxidase, which was measured by superoxide anion production; allopurinol decreased the enzyme activity. Enzymatic activity of nucleases participating in degradation of chromatin appears to be a component of prooxidant enzymatic systems of cell.

[Xanthine oxidase activity of thymocytes exposed to x-radiation]. / Ksantinoksidaznaia aktivnost' timotsitov pri deistvii rentgenovskogo oblucheniia.

Xanthine oxidase activity in thymocytes was studied at different time intervals after X-irradiation with doses of 0.5, 2 and 8 Gy. It was shown that 3 h and later after irradiation, dehydrogenase activity of the enzyme was converted into oxidase one. In the case of arresting the proteolysis by the effect of low doses (up to 0.5 Gy) and at early times the possibility of conversion of the enzyme into the dehydrogenase form was retained. The hyperactivity of the oxidase form of xanthine oxidase was probably a factor of expressing the proteolysis response and cell lysis.

[Changes in membrane proteins in the brain stem of the rat after deprivation of the paradoxical stage of sleep and prolongation of this stage during subsequent free behavior]. / Izmeneniia membrannykh belkov v stvole golovnogo mozga krys pri lishenii ikh paradoksal'noi fazy sna i prodolzhitel'nost' étoi fazy pri posleduiushchem svobodnom povedenii.

In REM-sleep-deprived rats, phenazepam (1.0 mg/kg) prevented the SH-group content increase in the brain stem membrane proteins, but induced undesirable sedative phenomena which, however, could be eliminated by simultaneous injections of sydnocarbum. The data obtained suggest that if the brain stem membrane proteins are protected against a denaturation-like alteration (characterized by the increase of SH-group content of these proteins) during REM-sleep deprivation, there is no "rebound" of this sleep phase after the end if the experiment in the condition of the unrestrained behavior of the rats.

[Kinetic properties of alkaline ribonuclease from rat brain]. / Nekotorye kineticheskie svoistva shchelochnoi ribonukleazy golovnogo mozga krys.

The rate of hydrolysis of polymeric yeast RNA by highly purified preparation of alkaline RNAse from the post-mitochondrial cellular fraction from the large hemispheres of rat brain was studied. It was shown that the reaction rate is maximal at the substrate concentration of 1-2 mg/ml. The curve of the reaction rate versus substrate concentration was found to be S-shaped. The value of S0,5 was equal to 0,138 mg/ml. The inhibition of alkaline RNAse by its specific protein inhibitor was of a non-competitive type.

[Effect of norepinephrine, GABA and cysteine on the complex of alkaline ribonuclease with its protein inhibitor]. / Vliianie noradrenalina, GAMK i tsisteina na kompleks shchelochnoi ribonukleazy s ee belkovym ingibitorom.

Norepinephrine GABA, cystein and SH-glutathione evoke a considerable decrease in the activity of alkaline RNase in the postmitochondrial fraction of the rat brain homogenate where the complex of this enzyme with its natural cytoplasmic protein inhibitor is preliminarily disturbed by the addition of pCMB. However these substances have no effect on the activity of alkaline RNase and its cytoplasmic protein inhibitor each taken separately. Evidently, the studied preparations may favour the reduction of the native state of the inactive complex of the enzyme with its inhibitor which was preliminarily disturbed by the pCMB addition.

[Isolation and several properties of purified preparations of the alkaline ribonuclease of the soluble fraction of rat cerebral hemispheres]. / Vydelenie i nekotorye svoistva ochishchennykh preparatov shchelochnoi ribonukleazy rastvorimoi fraktsii bol'shikh polusharii golevnogo mozga krys

Preparations of alkaline ribonuclease with optimum activity at pH 7,8 have been isolated from postmitochondrial fraction of the rat brain tissue by ammonium sulfate precipitation, 0.1 HCl extraction and following ammonium sulfate fractionation. Two preparations of this enzyme have been obtained by gel filtration through Sephadex G-25 and G-75, molecular weight of one of them (the most purified preparation) being about 13000. During electrophoresis the preparations moved from anode to cathode through polyacrylamide gel at pH 3.2. Bivalent cations (Ca2+, Mg2+) activated the enzyme preparations at concentration of u.10(-3)--5.10(-3) M. The degree of purification of preparations examined was 60 and 250 respectively.