Structural and functional analysis of poly(ADP ribose) polymerase: an immunological study

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Poly(ADP-ribose) polymerase (PARP) is a crucial nuclear enzyme involved in DNA repair and other cellular processes.
• Understanding PARP's structure and function is essential for developing targeted therapies.
• Monoclonal antibodies offer precise tools for studying enzyme epitopes and activities.

Purpose of the Study:

• To characterize three distinct epitopes on poly(ADP-ribose) polymerase (PARP) using specific monoclonal antibodies.
• To map these epitopes in relation to PARP's functional domains and assess antibody-mediated enzyme inhibition or activation.
• To investigate the intranuclear and interspecies immunoreactivity of PARP.

Main Methods:

• Monoclonal antibody production and characterization.
• Epitope mapping using proteolytic fragments (chymotryptic digestion).
• Enzyme activity assays, immunoaffinity chromatography, immunoblot analysis (Western blot), and immunofluorescence studies.

Main Results:

• Antibodies were mapped to specific fragments associated with the NAD-binding, DNA-binding, and automodification domains of PARP.
• One antibody inhibited PARP activity by 80% and was used for immunoaffinity purification; another enhanced activity by 30%.
• Species cross-reactivity varied, with one antibody showing broad reactivity (rat, Chinese hamster, human) and others being specific (human, bovine).

Conclusions:

• Monoclonal antibodies provide valuable tools for dissecting PARP structure, function, and localization.
• Specific epitopes correlate with distinct functional consequences, including enzyme inhibition and activation.
• PARP's association with nuclear material and variable epitope accessibility highlight its dynamic nuclear role.