Isopentenyl pyrophosphate isomerase from liver

Isopentenyl pyrophosphate isomerase (EC 5.3.3.2) was purified from extracts of pig liver by ammonium sulphate fractionation and by gel filtration. After about 20-fold purification the preparations were free of phosphatase and prenyltransferase (EC 2.5.1.1), the two enzymes that could have interfered...

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Bibliographic Details
Published in:Biochemical journal 1968-02, Vol.106 (4), p.835-840
Main Authors: Holloway, P W, Popják, G
Format: Article
Language:English
Subjects:
Alkenes - metabolism
Animals
Carbon Isotopes
Chromatography, Gas
Chromatography, Gel
Diphosphates - metabolism
Hydrogen-Ion Concentration
Isomerases - metabolism
Kinetics
Liver - enzymology
Magnesium
Manganese
Swine
Transferases
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Summary:Isopentenyl pyrophosphate isomerase (EC 5.3.3.2) was purified from extracts of pig liver by ammonium sulphate fractionation and by gel filtration. After about 20-fold purification the preparations were free of phosphatase and prenyltransferase (EC 2.5.1.1), the two enzymes that could have interfered with the assays. The isomerase has a distinct pH optimum at 6.0 and is activated by Mn(2+) in preference to Mg(2+). The K(m) value for isopentenyl pyrophosphate is 4x10(-6)m. The equilibrium of the reaction favours the formation of dimethylallyl pyrophosphate. The reversibility of the isomerase reaction was demonstrated directly by the formation of isopentenyl pyrophosphate from dimethylallyl pyrophosphate. It is suggested that two prenyl isomerases might exist, one involved in the synthesis of trans- and another in the synthesis of cis-polyprenyl substances.
ISSN:0264-6021
0306-3283
1470-8728
DOI:10.1042/bj1060835