... analogs with the diacid groups couldoccupy the initiator-binding site with enough affinity toinhibit rubber biosynthesis.As seen in Fig. 2, chaetomellic acid A (2) was able tointerfere with IPP ... perceived as FPP by both enzymes. In the range ofconcentrations of 6 incubated in the assays, the two rubbertransferases exhibit different degrees of negative coopera-tivity, with the P. argentatum ... brasiliensis. Compounds 2 and 6 reducedrubber transferase activity by 27% (when added at 180 lMin a 18,000-fold molar excess) and by 48% (when presentat 180 lMin a 180-fold molar excess), respectively.Compounds...