Extracted-ion chromatograms of products derived upon incubation of recombinant PCY1 with a synthetic peptide corresponding to presegetalin A1 [14–32]. Chromatograms showing the mass to charge ratio (m/z) values of the segetalin A product (m/z = 610.5, z = 1; green trace), of the linear [GVPVWA] product (m/z = 628.5, z = 1; red trace), of the presegetalin A1 [14–32] substrate (m/z = 993.2, z = 2; blue trace), and the presegetalin A1 [20–32] by-product (m/z = 688.5, z = 2; purple trace) are shown as indicated. The wild-type PCY1 used most of the presegetalin A1 [14–32] substrate to produce almost exclusively cyclic segetalin A product after a 1-h reaction.