Development of Peptide-Based Sirtuin Defatty-Acylase Inhibitors Identified by the Fluorescence Probe, SFP3, That Can Efficiently Measure Defatty-Acylase Activity of Sirtuin

Sirtuins
(SIRTs) are a family of nicotinamide adenine dinucleotide-dependent
histone deacetylases that serve as epigenetic regulators of many physiological
processes. Recent studies have shown that in addition to their well-known
deacetylase activity, sirtuins also exhibit deacylase activity, such
as demyristoylase activity. Here, we show that our previously reported
sirtuin fluorescence probe, SFP3, can measure the defatty-acylase
activity of SIRT1–3, enabling selective assay of the deacylase
activity. We further utilized this finding to develop the first inhibitors
of SIRT2 defatty-acylase activity. Notably, most previously reported
sirtuin inhibitors, including compound TM, AGK2, and
SirReal2, showed almost no SIRT2 defatty-acylase-inhibitory activity,
but are essentially specific deacetylase inhibitors. These results
suggest that the active sites catalyzing the deacetylase and defatty-acylase
activities of sirtuins may be independent.