Substrates and inhibitors of APAH from Mycoplana ramosa. Substrates include: acetylputrescine, acetylcadaverine, N1-acetylspermidine, N8-acetylspermidine, and N1-acetylspermine. Previously described33 inhibitors of APAH are analogues of the substrate N8-acetylspermidine bearing different metal-binding groups: trifluoromethylketone (1), thiol (2), or hydroxamic acid (3). New inhibitors reported in this study (4–7) are shorter hydroxamic acids with varying chain lengths.