Abstract
Living organisms have evolved various strategies to incorporate sulfur and selenium into bioactive natural products. These chalcogen-containing compounds serve important and diverse biological functions for their producers and many of them are essential medicines against infectious diseases and cancer. We review recent advances in the biosynthesis of some sulfur/selenium-containing natural products with a focus on the formation or cleavage of C-S/C-Se bonds. We highlight unusual enzymes that catalyze these transformations, describe their proposed mechanisms, and discuss how understanding these enzymes may facilitate the discovery and synthesis of novel natural products containing sulfur or selenium.