Project Summary / Abstract Alkaloid biosynthetic studies C-H activation is one of the key strategies to introduce structural and functional diversities into natural products in both chemical synthesis and biosynthesis. Non-heme iron enzymes are one of the key classes of C-H activating enzymes. In this work, we will conduct mechanistic studies of several non-hydroxylation reactions catalyzed by non-heme iron enzymes, including endoperoxidation, epoxidation, dehydrogenation, and oxidative C-S bond formation. These functional groups are key to the biological activities of many natural products. In Aim 1, we focus on the distal type of -ketoglutarate dependent non-heme iron enzymes because this is a relatively unexplored class of enzymes. There are two mechanistic models in explaining the activities of these enzymes and we will examine them using carefully selected enzymes (FtmOx1, CnsJ, and PhyH) because these enzymes all have two completely different activities. In Aim 2, we will conduct mechanistic studies on non-heme iron enzymes in ergothioneine and ovothiol biosynthesis. There are two mechanistic models proposed based on theoretical calculations. In this aim, using unnatural amino acid containing enzymes, we will differentiate between the two models.

Alkaloid biosynthetic studies NARRATIVE Alkaloid biosyntheses are known to be a gold mine for novel/unprecedented transformations. In this proposal, besides in-depth mechanistic characterization of the novel, unprecedented transformations (e.g., endoperoxidation and oxidative C-S bond formation), we will also apply these mechanistic information to guide our genome-mining efforts. Many of the compounds containing the functional groups (endoperoxide, epoxide, and thiols) have biological activities (e.g., anti-cancer, anti-infective, or having beneficial effects on many ageing associated diseases).