Structural biology and chemistry of the terpenoid cyclases

To date, a total of nine X-ray crystal structures of terpenoid cyclases and catalytic antibody cyclases have been reported. These enzymes are presented in order to provide information on their biosynthetic diversity. Focus is on monoterpene cyclases, sesquiterpene cyclases, diterpene cyclases, triterpene cyclases and antibody catalysis of cationic cyclization reactions. It is shown that given all the structural information on the family of enzymes acquired in the past eight years, the enzyme appears to play little chemical role once the cyclization cascade begins.