[Role of the mono(ADP)ribosylation of proteins in cellular regulation].

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].

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.

[ADP ribosylation of proteins and its role in regulating functional cellular activity].

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].

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.

[NADP+ catabolic enzymes in differentiating rabbit erythroid cells].

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.