Enzyme Mechanisms for Triterpene Cyclization: New Pieces of the Puzzle

Cationic polycyclization cascades: The stereoselective transformations of linear polyolefins to give cyclic triterpenes (see scheme) have fueled half a century of intense research. Structures of triterpene cyclases complexed with the substrate analogue 2-azasqualene and the reaction product lanosterol provide new insights into the elegant mechanisms of these enyzmes.