2',3'-dideoxynucleoside triphosphates (ddNTP) and di-2',3'-dideoxynucleoside tetraphosphates (ddNp4ddN) behave differently to the corresponding NTP and Np4N counterparts as substrates of firefly luciferase, dinucleoside tetraphosphatase and phosphodiesterases.

2',3'-Dideoxynucleosides (ddN) and their derivatives are currently used as antiretroviral compounds. Their active agents are the corresponding 2',3'-dideoxynucleoside triphosphates (ddNTPs) generated inside the cell by host kinases. Dinucleoside tetraphosphates (Np4Ns) are molecules of interest in metabolic regulation; their synthesis in vitro can be catalyzed by firefly luciferase.

Labeled adenosine(5')tetraphospho(5')adenosine (Ap4A) and adenosine(5')tetraphospho(5')nucleoside (Ap4N). Synthesis with firefly luciferase.

Labeled dinucleoside polyphosphates are not commercially available, in spite of being important molecules in metabolic regulation. Firefly luciferase (EC 1.13.

Diadenosine 5',5"-P1,P4-tetraphosphate (Ap4A), ATP and catecholamine content in bovine adrenal medulla, chromaffin granules and chromaffin cells.

The level of diadenosine 5',5"-P1-P4-tetraphosphate (diadenosine tetraphosphate or Ap4A), catecholamines, ATP and other nucleotides has been investigated in perchloric acid extracts of bovine adrenal medulla, chromaffin granules and cultured chromaffin cells. As a control, the amount of Ap4A and ATP has also been measured in human blood platelets. The following values (nmol/mg protein) were found in adrenal medulla: Ap4A, 0.

The mode of action of zaluzanin C, an inhibitor of translation in eukaryotes.

Zaluzanin C, a substance extracted from several species of the genus Zaluzania (Compositae), has been shown to inhibit protein synthesis in intact HeLa cells preferentially to DNA and RNA synthesis. "In vitro" protein synthesis was also blocked by zaluzanin C and the study of the effects of the drug on resolved model systems indicates that it inhibits enzymic translocation of peptidyl-tRNA specifically.

The mode of action of the antitumor drug bouvardin, an inhibitor of protein synthesis in eukaryotic cells.

Bouvardin is an antitumor drug that inhibits protein synthesis in intact eukaryotic cells and cell-free systems. Our present studies have shown that bouvardin acts at the level of the 80 S ribosome in a site somehow involved with the interaction of EF1 and EF2. Indeed bouvardin inhibits EF1-dependent binding of aminoacyl-tRNA and EF2-dependent translocation of peptidyl-tRNA but does not affect the nonenzymic translocation since this reaction does not require EF2.

[Mode of action of new antitumor compounds].

The antitumoral agents PR toxin, bouvardin and grandilactones A and B inhibit the growth of HeLa cells, and abolish polyphenylaline synthesis by polyuridylic acid in acellular eukaryotic systemns. However, only bouvardin and the PR toxin inhibit polypeptide synthesis in polysomes using endogenous m-RNA. In addition, grandilactones A and B inhibit the "fragment" reaction, which indicates that they affect specifically peptide bond formation, and the lack of effect on polysomes of these compounds would be due to the fact that, in polysomes, the substrate is bound to either the donor on the acceptor site.