In vivo measurement of the acetylation state of sirtuin substrates as a proxy for sirtuin activity

Evaluating the precise catalytic activity of sirtuin proteins in vivo is a challenging endeavor. Enzymological methods, including those employed in commercially available kits, require the isolation of immunopurified protein from cells or tissues, which can perturb regulatory protein-protein interactions as well as remove the enzyme from the reaction-altering effects of intracellular NAD⁺, nicotinamide, and O-acetyl-ADP ribose concentrations. As such, the measurement of the steady state acetylation status of select sirtuin substrates in vivo remains an important tool for evaluating changes in sirtuin activity. Here, we describe how to perform the analysis of the acetylation status of key SIRT1 and SIRT3 targets in rodent tissues and cultured cells.