Analyzing PARP1 Activity: Small Molecule Reactants and Attached Chains of Poly (ADP-Ribose)

Area of Science:

• Biochemistry
• Enzymology
• Analytical Chemistry

Background:

• Poly(ADP-ribosyl)ation (PARylation) is a crucial post-translational modification mediated by PARP enzymes.
• Understanding the dynamics of PARylation requires precise quantification of its substrates, byproducts, and products.
• Existing methods may not fully resolve the diverse outcomes of PARylation, including chain length and branching.

Purpose of the Study:

• To develop and validate a high-pressure liquid chromatography (HPLC) method for comprehensive analysis of PARylation.
• To quantify key molecules involved in PARylation, including NAD+, nicotinamide, and ADPR.
• To differentiate and quantify various PARylation products, including chain ends, middles, and branches.

Main Methods:

• High-pressure liquid chromatography (HPLC) coupled with appropriate detection methods.
• Enzymatic or chemical digestion of poly(ADP-ribose) (PAR) chains to yield measurable fragments.
• Quantification of nicotinamide (Nam) and adenosine diphosphate ribose (ADPR).

Main Results:

• The developed HPLC method accurately quantifies NAD+ (substrate), nicotinamide (byproduct), and ADPR (hydrolysis product).
• The method successfully quantifies digested PARylation products, categorizing them into ends, middles, and branches.
• The technique allows for the dissection of PARP enzyme activity and the partitioning of PARylation outcomes.

Conclusions:

• This HPLC method provides a robust tool for detailed analysis of PARylation.
• It enables a deeper understanding of PARP1 and PARP2 activity and the regulation of PARylation.
• The method facilitates research into the biological roles of PARylation by dissecting product formation and distribution.