Fig. 4: Enzymatic activity of PsiM.
a In vitro activity assay monitored by means of single ion chromatograms, revealing accumulation of the monomethylated intermediate baeocystin. Upper lane: overlaid chromatograms of authentic standards. Bottom lane: a typical PsiM-catalysed methylation reaction after 2 h, represented by chromatograms for m/z 257 [M + H]+ (red, norbaeocystin), m/z 271 [M + H]+ (grey, baeocystin), and m/z 285 [M + H]+ (blue, psilocybin). b Michaelis-Menten kinetics of the first (red; Km = 575 ± 100 µm, kcat = 0.11 ± 0.01 min–1) and the second methylation reaction (grey, Km = 492 ± 154 µm, kcat = 0.06 ± 0.01 min−1). Data are presented as mean values of three independent experiments (n = 3), with error bars corresponding to the sample standard deviation (SD). Source data are provided in the supplementary Source Data file.
