Potassium-stimulating mechanism of geranylgeranyl diphosphate synthase of Methanobacterium thermoformicicum SF-4

J Biochem. 1993 Sep;114(3):389-92. doi: 10.1093/oxfordjournals.jbchem.a124186.


The catalytic properties of geranylgeranyl diphosphate (GGPP) synthase [EC] purified from Methanobacterium thermoformicicum SF-4 were studied by kinetic procedures. The plots of 1/v versus 1/[S] and inhibition patterns by enzyme reaction products, PPi and GGPP, showed that the GGPP synthase reaction mechanism is an ordered-sequential Bi Bi one. Monovalent cations at low concentration (0.05 M) enhanced the enzyme activity, but at high concentration (0.4 M) they were inhibitory, except for K+. The K+ ion was found to be a modifier forming a parallel reaction pathway and accelerated the binding of substrates to the enzyme, especially the binding of isopentenyl diphosphate (IPP). When substrate concentrations are near the Km values, the rate-limiting step of the GGPP synthase reaction may be the substrate-binding step, probably the IPP-binding step, rather than the conversion step of the enzyme-farnesyl diphosphate-IPP complex to the enzyme-PPi-GGPP complex.

MeSH terms

  • Alkyl and Aryl Transferases*
  • Cations, Monovalent / pharmacology
  • Farnesyltranstransferase
  • Kinetics
  • Methanobacterium / enzymology*
  • Potassium / pharmacology*
  • Transferases / antagonists & inhibitors
  • Transferases / drug effects*


  • Cations, Monovalent
  • Transferases
  • Alkyl and Aryl Transferases
  • Farnesyltranstransferase
  • Potassium