Synthesis of Putative Intermediates on the Monensin Biosynthetic Pathway and Incorporation Experiments with the Monensin‐Producing Organism

Abstract

Abstract As a direct test of the Cane ‐ Westley hypothesis concerning the mode of assembly of ether rings in the polyether class of ionophore antibiotics, we describe experiments culminating in the synthesis of three putative intermediates on the monensin biosynthetic pathway and incorporation experiments with these materials and the monensin‐producing organism Streptomyces cinnamonensis . The putative intermediates synthesised include the trienes [21‐ 3 H]‐ 7 and [13‐ 3 H]‐ 10 , and the diene [9‐ 3 H]‐ 11 . The results of the incorporation experiments conducted with whole cell cultures suggest that [13‐ 3 H]‐ 10 and [21‐ 3 H]‐ 7 are unable to cross the intact cell membrane of S. cinnamonensis , whereas diene [9‐ 3 H]‐ 11 can gain entry to the cellular interior, but is then degraded efficiently, most likely by a pathway closely related to β‐oxidation, without being specifically incorporated into the antibiotic.