Natural occurrences Isoprene

1 natural occurrences

1.1 plants

1.1.1 regulation


1.2 other organisms

natural occurrences

isoprene produced , emitted many species of trees (major producers oaks, poplars, eucalyptus, , legumes). yearly production of isoprene emissions vegetation around 600 million metric tons, half tropical broadleaf trees , remainder shrubs. equivalent methane emissions , accounts around one-third of hydrocarbons released atmosphere.

plants

isoprene made through methyl-erythritol 4-phosphate pathway (mep pathway, called non-mevalonate pathway) in chloroplasts of plants. 1 of 2 end products of mep pathway, dimethylallyl pyrophosphate (dmapp), catalyzed enzyme isoprene synthase form isoprene. therefore, inhibitors block mep pathway, such fosmidomycin, block isoprene formation. isoprene emission increases dramatically temperature , maximizes @ around 40 °c. has led hypothesis isoprene may protect plants against heat stress (thermotolerance hypothesis, see below). emission of isoprene observed in bacteria , thought come non-enzymatic degradations dmapp.

regulation

isoprene emission in plants controlled both availability of substrate (dmapp) , enzyme (isoprene synthase) activity. in particular, light, co2 , o2 dependencies of isoprene emission controlled substrate availability, whereas temperature dependency of isoprene emission regulated both substrate level , enzyme activity.

other organisms

isoprene abundant hydrocarbon measurable in breath of humans. estimated production rate of isoprene in human body 0.15 µmol/(kg·h), equivalent approximately 17 mg/day person weighing 70 kg. isoprene common in low concentrations in many foods.

chemical structure of cis-polyisoprene, main constituent of natural rubber