MALDI Imaging Assisted Discovery of a Di‐O‐glycosyltransferase from Platycodon grandiflorum Root

Abstract

A matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) assisted genome mining strategy was developed for the discovery of glycosyltransferase (GT) from the root of Platycodon grandiflorum. A di-O-glycosyltransferase PgGT1 was discovered and characterized that is capable of catalyzing platycoside E (PE) synthesis through the attachment of two β-1,6-linked glucosyl residues sequentially to the glucosyl residue at the C3 position of platycodin D (PD). Although UDP-glucose is the preferred sugar donor for PgGT1, it could also utilize UDP-xylose and UDP-N-acetylglucosamine as weak donors. Residues S273, E274, and H350 played important roles in stabilizing the glucose donor and positioning the glucose in the optimal orientation for the glycosylation reaction. This study clarified two key steps involved in the biosynthetic pathway of PE and could greatly contribute to improving its industrial biotransformation.

Distribution of active ingredients and quality control of Forsythia suspensa with AP‐MALDI mass spectrometry imaging

“…Distribution of active ingredients in whole fruitsTraditionally, the active ingredients of Chinese herbs were evaluated with their weight-averaged content with LC/GC methods.Recently, the distribution of active ingredients in Chinese herbs has attracted the attention of pharmacologists because the distribution of active ingredients may indicate the most active parts and evaluate the effects of production and processing technology on the quality of Chinese herbs 27,28. Figure 1 illustrates the distribution of 15 typical ingredients in the whole green fruit.…”