Isoprene

Isoprene is the chemical 2-methyl-1,3-butadiene. It is a common structural motif in biological systems. The terpenes (for example, the carotenes are tetraterpenes) are derived from isoprene, as is Coenzyme Q. Also derived from isoprene are phytol, retinol (vitamin A) , tocopherol (vitamin E), dolichols, and squalene. Heme A has an isoprenoid tail, and lanosterol, the sterol precursor in animals, is derived from squalene and hence from isoprene. The functional isoprene units in biological systems are dimethylallyl pyrophosphate (DMAPP) and its isomer isopentenyl pyrophosphate (IPP), which are used in the biosynthesis of terpenes and lanosterol derivatives.

In virtually all organisms, isoprene derivatives are synthetised by the HMG-CoA reductase pathway

According to research in 2004 by the UK Natural Environment Research Council (NERC), isoprene is released by vascular plants in extreme hot weather, catalysing the conversion of nitrogen oxide, an atmospheric pollutant, to ozone, a gas that irritates the lungs, particularly in asthma sufferers.