FIGURE 10.

Summary of the reactions catalyzed by ORS, from acetyl-CoA as a starter substrate. ^aIn the presence of C. sativa OAC, methyl tetra-β-ketide CoA, released from the ORS active site, undergoes aldol condensation to form a C2–C7 linkage. The following aromatization and thioester hydrolysis could take place in solution to yield OSA. In the absence of OAC, the tetraketide CoA would be spontaneously cyclized into orcinol.