ISOPRENE SYNTHESIS BY PLANTS AND ANIMALS

Isoprene is emitted from both plants and animals at significant rates. There is evidence for a specific enzyme, isoprene synthase, that prod uces isoprene from dimethyl allyl pyrophosphate, one of the intermedia tes involved in the synthesis of higher-order isoprenoids such as chol esterol, carotenoids and monoterpenes (for example, pine scent). The r ole of isoprene in animals is unknown, but there is recent evidence th at isoprene helps protect plant membranes involved in photosynthesis f rom thermal damage. Isoprene emission from plants is a natural process that contributes more hydrocarbon to the atmosphere than all of the a nthropogenic hydrocarbons.