Pyrophosphomevalonate decarboxylase

PROPIONYL-CoA SYNTHETASE PYROPHOSPHATASE, INORGANIC PYROPHOSPHOMEVALONATE DECARBOXYLASE... 

SQUALENE SYNTHASE SULFATE ADENYLYLTRANSFERASE UBIQUITIN-PROTEIN LIGASES PYROPHOSPHATE FRUOTOSE-6-PHOS-PHATE 1-PHOSPHOTRANSFERASE PYROPHOSPHOMEVALONATE DECARBOXYLASE... 

Full details have appeared of the rubber enzyme phosphomevalonate kinase (EC 2.7.4.2) and 5-pyrophosphomevalonate decarboxylase (EC 4.1.1.33). 

Several of the individual enzymes of the early steps of terpene biosynthesis have been isolated. Mevalonic kinase [EC 2.7.1.36, (1) — (2)] has been prepared from several sources, for example Phaseolus vulgaris and pig liver. A feed-back control mechanism was suggested for the animal enzyme. Kekwick determined detailed kinetic data for pyrophosphomevalonate decarboxylase [EC 4.1.1.33,... 

Pyrophosphomevalonate decarboxylase (EC 4.1,1.33 di-phosphomevalonate decarboxylase) 3-Carboxy-cis-cis-muconate cyclo-isomerase (EC 5.5.I.2)... 

The conversion of mevalonate (1) to isopentenyl pyrophosphate (IPP) (4) involves two consecutive phosphorylations at position 5 by successive action of mevalonate kinase (EC 2.7.4.2) and a decarboxylation and dehydration of the tertiary alcohol group by mevalonate 5-pyrophosphate decarboxylase (EC 4.1.1.33) (Fig. 18.4) (Crotean Johnson, 1985 Gershenzon and Croteau, 1990). One mole of ATP is required for each phosphorylation reaction. Mevalonate kinase converts mevalonic acid to (5/ )-phosphomevalonate (5). The second phosphorylation is catalyzed by phospho-mevalonate kinase. The subsequent decarboxylation and dehydration is mediated by the enzyme mevalonate diphosphate decarboxylase (di- or pyrophosphomevalonate decarboxylase EC 4,1.1.3.3) this enzyme requires Mg " or Mn + and ATP for activity (Beale and MacMillan, 1988 Harrison, 1988). All three of these enzymes are found in a number of plants. 

Action of the enzyme pyrophosphomevalonate decarboxylase on 5-pyrophosphomevalonate results in the consumption of a third equivalent of ATP and the simultaneous dehydration and decarboxylation (loss of carbon dioxide, CO2) of the pyrophosphomevalonate. Isopentenyl diphosphate results... 

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