[Role of the mono(ADP)ribosylation of proteins in cellular regulation]. / Rol' mono(ADF)ribozilirovaniia belkov v reguliatsii aktivnosti kletok.

In addition to its well established role as a cofactor in redox reactions, NAD+ serves also as a substrate for a ubiquitous group of enzymes called ADP-ribosyltransferases. These enzymes are found in the cytosol and in the nucleus of eukaryotic cells, they are involved as components of pathogenic bacterial toxins, and as part of a mechanism for inactivating host cell protein biosynthetic machinery in bacteriophage-infected cells. An overview of mono(ADP)ribosylation reactions is provided.

[NADPase and NADase in the peritoneal macrophages of mice]. / NADFaza i NADaza peritoneal'nykh makrofagov myshei.

Murine peritoneal macrophages are able to hydrolyse NAD+ and NADP+. The NADPase activity exceeds that of NADase by 22-24%. The pH optima for both the enzymes are, respectively, 6.0 and 7.0. NAD hydrolysis is considerably activated by Mg2+, whereas NADP hydrolysis remains not affected. NAD+ does not change NADPase activity, while NADase activity is inhibited by NADP by 25-30%. A diazonium salt of sulfanilic acid, known to be an inhibitor of cell plasma membranes, does not affect NADP+ hydrolysis and causes a 20-30% retardation of NAD+ hydrolysis. The data obtained suggest that murine peritoneal macrophages contain two hydrolytic enzymes: NADase and NADPase.

[ADP ribosylation of proteins and its role in regulating functional cellular activity]. / ADF-ribozilirovanie belkov i ego rol' v reguliatsii funktsional'noi aktivnosti kletok.

New data are presented on ADP-ribosylation of nuclear proteins, which is one of the paths of their postsynthetic modifications. The importance of this reaction for DNA cell cycle regulation are discussed. The structure of mono- and poly(ADPRib), the properties of their synthesis and degradation catalyzing enzymes, and the nature of the modified proteins are considered.

[Synthesis and breakdown of pyridine nucleotide coenzymes in the cell nuclei of guinea pig kidneys in diphtheria intoxication]. / Sintez i raspad piridinnukleotidnykh kofermentov v iadrakh kletok pochek morskoi svinki pri difteriinoi intoksikatsii.

The effect of diphteria toxin on the synthesis and degradation of NAD+ and the hydrolysis of NADP+ in the nuclei of guinea pig kidney were studied. Treatment of animals with diphteria toxin (DT) results in considerable reduction of NADpyrophosphorylase activity, which starts 12 hours after incubation and is minimal (50% of that of the control animals) 18 hours after it. During this time interval DT does not affect the activity of NADase and decreases that of NADPase in the nuclei. Thus under diphterial intoxication a decrease of NADPase activity, the synthesis of NAD+ being reduced, probably provides for kidney cells more favourable conditions for maintenance of their synthetic reactions and for restoration of their normal metabolism. It was found that the non-ionic detergent Triton X-100 promotes the NADpyrophosphorylase activity in cell nuclei of intact animals by 40% (on the average) and does not affect the NAD+ synthesis in DT injected animals. Therefore DT not only reduces the nuclear NADpyrophosphorylase activity but also affects the nuclear envelope. The alteration of nuclei under DT treatment is suggested by the decrease of their histone content (30% on the average as compared with the control). The decrease of NADpyrophosphorylase activity under DT intoxication can be considered as an adaptive reaction limiting the availability of NAD+ as the substrate of the EF2 mono (ADP-ribosilation) which results in its unability to promote translation.

[NADP+ catabolic enzymes in differentiating rabbit erythroid cells]. / Fermenty katabolizma NADF+ v differentsiruiushchikhsia éritroidnykh kletkakh krolika.

NADP-glycohydrolase and NADP-pyrophosphates activities were examined during the rabbit erythroid cell differentiation. The former is high in erythroblast lysates, especially in the erythroblast nuclei. As erythroid cell maturation proceeds, the activity of NADP-glycohydrolase decreases. At the first step (erythroblast-reticulocyte transformation), this activity falls down more than by 20 times, whereas at the second step (reticulocyte-erythrocyte transformation) it decreases no more than twice. NADP-glycohydrolase is associated with the stroma of erythroid cells throughout their maturation, being bound with the nucleus in erythroblasts. NADP-pyrophosphatase activity has been detected in reticulocytes and mature cells only. The role of NADP- and NAD-glycohydrolases for characterization of the intracellular metabolic pools is discussed.

[Enzymes of NAD+ catabolism in differentiating rabbit erythroid cells]. / Fermenty katabolizma NAD+ v differentsiruiushchikhsia éritroidnykh kletkakh krolika.

A study was made of the hydrolysis of NAD+ in the process of rabbit erythroid cell differentiation. Activities of NAD-hydrolase and NAD-pyrophosphatase, examined during maturation of erythroid cells, demonstrated a more significant decrease in the course of erythroblast-reticulocyte transformation, than at the next step of erythropoesis (reticulocyte-erythrocyte transformation). Both enzymes are strongly associated with the stroma. Under discussion is a question of the possible role of NAD+ catabolism.

[NAD+ synthesis in the isolated kidney cell nuclei of dogs after the intravenous administration of amphotericin B]. / Sintez NAD+ v izolirovannykh iadrakh kletok pochek sobak posle vnutrivennogo vvedeniia amfoteritsina B.

A study was made of the synthesis of nicotinamide adenine dinucleotide (NAD+) in the nuclei of kidney cells of dogs under normal conditions and upon the effect of the polyenic antibiotic amphotericin B. An active NAD-pyrophosphorylase has been found in the nuclei of kidney cells. It has been established that a intervenous introduction of amphotericin B stimulates NAD+ production. Amphotericin B also causes a decrease in the amount of histones in the nucleus. In the case of the nuclear membrane damage by a non-ionic detergent Triton X-100, no increase in the synthesis of NAD+ has been observed in the nuclei of kidney cells of animals treated with antibiotics, as opposed to the control ones. Under discussion is a question of a possible mechanism of the effect of polyenic antibiotics on the synthesis and metabolic activity of NAD+.

[Poly (ADP-ribose), ADP-ribosylation of proteins and regulation of cell activity]. / Poli(ADF-riboza), ADF-ribozilirovanie belkov i reguliatsiia kletochnoi aktivnosti.

The nature of a before unknown biological activity of NAD as a substrate in protein modification reaction is considered. Upon enzymatic digestion of NAD its adenosinediphosphate ribose (ADPR) part is transferred to acceptor proteins. ADPR in its mono- or polymeric form is covalently linked to proteins at the expense of NAD's high energy bound. Negatively charged ADPR, in association with a protein, is able to alter the charge, conformation and biological activity of the latter. The reaction is important in structural rearrangements of chromatin, in the synthesis and repair of DNA, in cell growth and differentiation and in the mechanisms of actions of actions of bacterial toxins.

[Distribution and activity of certain dehydrogenases in the erythropoietic process in pigeons]. / Raspredelemie i aktivnost' nekotorykh degidrogenaz v protsesse éritopoéza u golubei

Cytochemical methods were applied for detecting of distribution and dynamics of dehydrogenase activity (H- and M-subunits of lactate dehydrogenase, malate and succinate dehydrogenase) during maturation of pigeon erythrocytes. In the erythroblasts the above enzymes were seen in the whole cell; in reticulocytes - only around the nucleus; in erythrocytes - on the border line between the nucleus and the cytoplasm. The cytophotometric data show a decrease in enzymatic activity during maturation being more significant in the period from the erythroblast to reticulocyte development than from the reticulocyte to erythrocyte development.

[Synthesis of nicotinamide adenine dinucleotide in the nuclei of pigeon erythrocytes]. / Sintez nikotinamidadenindinukleotida v iadrakh éritrotsitov golubia

The nuclei of pigeon erythrocytes are capable of synthesizing NAD from nicotinamid-mononucleotides and ATP. Some data on the kinetics of NAD-pyrophosphorylase have been obtained: the optimal concentration of nuclei and the effect of various incubation time. The pretreatment of nuclei by Triton X-100, or by ultrasonics enhances NAD synthesis. The results suggest that cyclic 3',5'-AMP (Fluka) may have no effect on NAD synthesis. The control of the cell metabolism by NAD formation is considered.