BIOSYNTHESIS OF CYCLIC MONOTERPENES IN HIGHER PLANTS. THE RETENTION OF THE C-5 HYDROGEN ATOMS OF MEVALONATE DURING ITS INCORPORATION INTO THE CYCLIC MONOTERPENES
The 3H/14C ratio of [5-3H2, 2- 14C]mevalonate was preserved in limonene, perillaldehyde, and camphor biosynthesized by higher plants from the mevalonate. This indicates that the cyclic monoterpenes are biosynthesized through such a pathway that involves the cyclization of such an intermediate as retaining all the C-1 and C-5 tritium atoms of geranyl pyrophosphate derived from the mevalonate.