Biosynthesis of juvenile hormone in the cecropia moth. labelling pattern from 1‐[ 14 C]‐propionate through degradation to single carbon atom derivatives

In the adult made cecropia moth, 1‐[ 14 C]‐propionate is incorporated specifically into juvenile hormone I ( 1 ). By chemical degradation it was found that only C(7) and C(11) are labelled, each carbon atom bearing 50% of the radioactivity originally present in JH‐I. It is concluded that propionate serves as a precursor of homomevalonate, which in turn is a precursor for JH‐I. Application of 2‐[ 14 C]‐propionate and 3‐[ 14 C]‐propionate leads to extensive randomization of the label. Apparently propionate is metabolized such that C(2) and C(3) can be reused as smaller fragments–probably acetate–while C(1) is either highly diluted or removed from the propionate in a metabolically inactive form.