Fig. 5.
S. aciditrophicus sirtuin SYN_00042 shows in vitro deacylase activity.A, MALDI-MS of insulin and modified insulin deacylated by sirtuin (Syn_00042). The peak corresponding to “Glutarylated Nε - Lysine” reflects the mass shift from three glutaryl modifications (+342 Da), two at the N-termini and one at the single lysine. B, ESI-MS of the 4+ charge states 0, 2, 15 and 60 min after sirtuin addition. Purple peak clusters (left) correspond to insulin modified at the two N-termini; red clusters identify insulin modified at all three sites. Ammonium adducts (+17 Da) are also present. ESI, electrospray ionization; MALDI, matrix-assisted laser desorption/ionization; MS, mass spectrometry.