Fig. 7.

Analysis of HiPMO1 reaction products hydrolyzed by beta-glucuronidase and beta-glucosidase using SIM LC–MS/MS analysis. a SIM LC–MS showing extracted ion chromatograms and the corresponding mass spectra of glucuronic acid and saccharic acid (saccharic acid lactone). In positive mode: saccharic acid (m/z 210 + H⁺). In negative mode: glucuronic acid (m/z 194 − H⁺) and saccharic acid lactone (m/z 192 − H⁺). b The SIM MS/MS spectra showing fragmentation ions of the parent ions at m/z 192.8 for glucuronic acid (m/z 194 − H⁺) and at m/z 190.9 for saccharic acid lactone (m/z 192 − H⁺). Loss of [H] and [H₂O] and addition of [H] is common in carbohydrate fragmentations using LC–MS/MS in the negative ion mode [38]. The loss of [H], [H₂O], [CHO], and [COOH] and the addition of [H] from the parent ions of glucuronic acid (m/z 194 − H⁺) and saccharic acid lactone (m/z 192 − H⁺), generating various fragmentation ions. The MS/MS spectra of saccharic acid (m/z 210 + H⁺) were not shown, likely due to the low intensities