( ) endo fenchol synthase

In enzymology, a (−)-endo-fenchol synthase (EC 4.2.3.10) is an enzyme that catalyzes the chemical reaction

Thus, the two substrates of this enzyme are geranyl diphosphate and H₂O, whereas its two products are (−)-endo-fenchol and diphosphate.

This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on phosphates. The systematic name of this enzyme class is geranyl-diphosphate diphosphate-lyase [cyclizing, (−)-endo-fenchol-forming]. Other names in common use include (−)-endo-fenchol cyclase, and geranyl pyrophosphate:(−)-endo-fenchol cyclase. This enzyme participates in monoterpenoid biosynthesis.