Stearoyl-CoA Δ9 desaturase activity assays for DesA3 variants expressed in M. smegmatis. Lanes: L1, the total lysate expressing DesA3-myc (containing a C-terminal myc tag); L2, native DesA3-LAA; L3, DesA3-DKD; L4, DesA3-LEA. The positions of migration of the substrate (18:0), product (18:1), and a side product in the thin-layer chromatography separation are indicated.