2OacetylADPribose

2OacetylADPribose, commonly written as 2'-O-acetyl-ADP-ribose (OAADPr), is a biochemical metabolite produced during NAD+-dependent deacetylation reactions catalyzed by sirtuin enzymes. In these reactions, an acetyl group is removed from a substrate protein or peptide, generating nicotinamide and OAADPr as byproducts.

Biosynthesis and context: OAADPr is formed when sirtuins transfer the acetyl group from an acetylated substrate to the ADP-ribose moiety derived from NAD+. This results in a molecule in which the acetyl group is covalently attached to the 2'-oxygen of the ribose portion of ADP-ribose. OAADPr formation links protein deacetylation to ADP-ribose metabolism and cellular energy state, and OAADPr levels can reflect metabolic conditions that influence sirtuin activity.

Structure and naming: OAADPr consists of ADP-ribose with an acetyl group esterified to the 2'-OH of the ribose. This structural modification distinguishes OAADPr from unmodified ADP-ribose and from other acetylated metabolites produced in related pathways.

Occurrence and significance: OAADPr has been detected across diverse organisms, including bacteria, yeast, and mammals, where it is studied in the context of sirtuin biology and cellular signaling. While initial research established OAADPr as a product of deacetylation, its precise physiological roles remain an active area of investigation. Proposed functions include participation in signaling networks and links to chromatin regulation, transcription, and stress responses, though mechanisms and importance can vary by organism and context.

Metabolism and turnover: OAADPr can be further metabolized by specific hydrolases or phosphodiesterases, yielding downstream metabolites such as ADP-ribose and acetate. Its turnover reflects the interplay between NAD+-dependent deacetylation, acetylation status, and cellular energy balance.