AveC catalyzes the stereospecific spiroketalization of a dihydroxy-ketone polyketide intermediate in the biosynthetic pathway of Avermectin, a potent antiparasitic agent. Additionally, it has a unique dehydration activity that serves to determine the regiospecific saturation pattern for spiroketal diversity [1]. MeiC, the counterpart in the biosynthesis of AVE-like meilingmycin, also has spirocyclase activity, but lacks the dehydratase activity.

1: Spiroketal formation and modification in avermectin biosynthesis involves a dual activity of AveC. Sun P, Zhao Q, Yu F, Zhang H, Wu Z, Wang Y, Wang Y, Zhang Q, Liu W; J Am Chem Soc. 2013;135:1540-1548. PMID:23294008