PAR & PARP Assays

Schematic Representation of the Function of PARP Following DNA Damage.
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Schematic Representation of the Function of PARP Following DNA Damage. Following DNA damage, PARP catalyzes the synthesis of PAR chains on itself and adjacent nuclear proteins. This modification is involved in signaling DNA damage and aiding in DNA repair in normal, viable cells (right). During apoptosis, PARP is cleaved by caspases and can no longer be activated by DNA damage, preventing apoptotic cells from repairing their DNA (left).

Poly (ADP-ribose) Polymerase (PARP) is an abundant enzyme present in all somatic cells that detects and signals DNA damage to repair mechanisms. It is activated in response to single strand DNA breaks and subsequently attaches to regions of damaged DNA. PARP then catalyzes the synthesis of poly (ADP-ribose) (PAR) chains on itself and adjacent nuclear proteins, such as histones. PAR chains serve as a signal for other DNA repair enzymes. After the DNA is repaired, the PAR chains are degraded by PAR glycohydrolase (PARG).

PAR synthesis utilizes NAD+. Extensive DNA damage can lead to the depletion of intracellular NAD+ and energy depletion-induced necrosis. In this regard, PARP is specifically cleaved by caspases so that it is no longer active, preventing DNA repair and promoting apoptotic processes.

Available Kits

Supplemental PARP Assay Reagents

6-Biotin-17-NAD (Catalog # 4670-500-01)

Non-isotopic alternative to radiolabeled NAD for studies requiring this substrate.

Anti-PAR Affinity-purified Polyclonal Antibody (Catalog # 4336-APC-050)

Used to detect ribosylated proteins by Western blot.

Anti-PARP Monoclonal Antibody (Catalog # 4338-MC-50)

Used to detect both full length and the 85 kDa cleavage fragment of PARP by Western blot or immunohistochemistry.

PARP Enzyme-High Specific Activity (Catalog # 4668-100-01, 4668-500-01)

Positive control for both Western blot analysis of PARP and PARP assay kits. Also recommended for drug discovery applications.

Poly(ADP-ribose) Polymer/pADPr (Catalog 4336-100-01)

Western blotting standard.