kcat/Km,NAD determined for SIRT1, SIRT2, SIRT3, and SIRT6 in the presence of acetyl-, hexanoyl-, decanoyl-, and myristoyl-lysine H3K9 peptides. Calculated parameters determined from non-linear regression fits to Michaelis-Menten shown below. **kcat/Km,NAD with acetylated peptide for SIRT6 was not measured due to prohibitively high peptide substrate necessary to saturate the reaction (n ≥ 3, ± standard deviation of mean)