Purification of Protein-Free and Protein-Linked Poly(ADP-Ribose) from Biochemical Reactions and from Human Cells

Poly(ADP-ribose) or PAR regulates multiple aspects of cell biology, both as an independent signaling molecule and as a modification on biomolecules. As a posttranslational modification, PAR can modulate the biochemical properties of target proteins. Isolated free PAR molecules function in cellular signaling. This chapter describes two methods to isolate and purify free PAR and protein-linked PAR from biochemical reactions, one using chemical fractionation and another using physical separation. A method to isolate free PAR and protein-linked PAR from human cells is also presented. These methods allow monitoring of free PAR and protein-linked PAR levels under different biochemical conditions or in response to different cellular stimuli.