[Poly (ADP-ribose), ADP-ribosylation of proteins and regulation of cell activity].

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.