Cyclic imines form a general class of chemical compounds that includes the metabolites of drugs used to treat a wide variety of conditions. β-carboline alkaloids in particular have been extensively studied as medicines, showing excellent bioactivities, and have been used in treatments for hypertension. However, despite significant understanding of the biosynthesis that forms cyclic imines, the degradation of these compounds is not well understood. Now, researchers from the University of Tsukuba have isolated cyclic imine-metabolizing microorganisms from soil, identified a cyclic imine-metabolizing enzyme, and proposed its catalytic mechanism. Their findings are published in Nature Communications.