IRMPD-based quantification of ER-catalyzed saturation and cyclopropanation reactions

The quantification of enzyme reactions with protein-linked substrates and products is highly challenging. Here we report a facile technique that allowed us to precisely quantify ratios of ACP-linked species in the ER-catalyzed saturation and cyclopropanation reactions by using the IRMPD-based method (Figure 1). This technique has wide application in natural product biosynthesis studies.