Quantitative studies of inhibitors of ADP-ribosylation in vitro and in vivo.
J Biol Chem
; 264(8): 4312-7, 1989 Mar 15.
Article
em En
| MEDLINE
| ID: mdl-2538435
ABSTRACT
The ADP-ribosyl moiety of NAD+ is consumed in reactions catalyzed by three classes of enzymes poly(ADP-ribose) polymerase, protein mono(ADP-ribosyl)transferases, and NAD+ glycohydrolases. In this study, we have evaluated the selectivity of compounds originally identified as inhibitors of poly(ADP-ribose) polymerase on members of the three classes of enzymes. The 50% inhibitory concentration (IC50) of more than 20 compounds was determined in vitro for both poly(ADP-ribose) polymerase and mono(ADP-ribosyl)transferase A in an assay containing 300 microM NAD+. Of the compounds tested, benzamide was the most potent inhibitor of poly(ADP-ribose) polymerase with an IC50 of 3.3 microM. The IC50 for benzamide for mono(ADP-ribosyl)transferase A was 4.1 mM, and similar values were observed for four additional cellular mono(ADP-ribosyl)transferases. The IC50 for NAD+ glycohydrolase for benzamide was approximately 40 mM. For seven of the best inhibitors, inhibition of poly(ADP-ribose) polymerase in intact C3H1OT1/2 cells was studied as a function of the inhibitor concentration of the culture medium, and the concentration for 50% inhibition (culture medium IC50) was determined. Culture medium IC50 values for benzamide and its derivatives were very similar to in vitro IC50 values. For other inhibitors, such as nicotinamide, 5-methyl-nicotinamide, and 5-bromodeoxyuridine, culture medium IC50 values were 3-5-fold higher than in vitro IC50 values. These results suggest that micromolar levels of the benzamides in the culture medium should allow selective inhibition of poly(ADP-ribose) metabolism in intact cells. Furthermore, comparative quantitative inhibition studies should prove useful for assigning the biological effects of these inhibitors as an effect on either poly(ADP-ribose) or mono(ADP-ribose) metabolism.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Adenosina Difosfato Ribose
/
ADP Ribose Transferases
/
NAD/ Nucleosidase
/
Inibidores de Poli(ADP-Ribose) Polimerases
Limite:
Animals
Idioma:
En
Ano de publicação:
1989
Tipo de documento:
Article