These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Reaction mechanism of phosphoenolpyruvate carboxylase. Bicarbonate-dependent dephosphorylation of phosphoenol-alpha-ketobutyrate.
    Author: Fujita N, Izui K, Nishino T, Katsuki H.
    Journal: Biochemistry; 1984 Apr 10; 23(8):1774-9. PubMed ID: 6326809.
    Abstract:
    Phosphoenolpyruvate carboxylase (EC 4.1.1.31) of Escherichia coli was found to catalyze the cleavage reaction of phosphoenol-alpha-ketobutyrate, a potent competitive inhibitor with the substrate, to yield inorganic phosphate and alpha-ketobutyrate. The rate of phosphate liberation was about 1/20 th of that in the normal reaction with phosphoenolpyruvate. Although HCO3- and Mg2+ were the necessary components in this reaction as in the normal reaction, no CO2 fixation could be detected. When the reaction was carried out in the presence of [18O]HCO3-, multiple incorporations of 18O atoms into the liberated phosphate molecule were observed. The molar proportions of phosphate having one, two, and three 18O atoms were 70, 25, and 5%, respectively. No multiple but only one 18O atom incorporation was observed when phosphoenolpyruvate was used as a substrate. These results suggest that the liberation of phosphate can proceed without CO2 fixation, being not consistent with the concerted mechanism [ Maruyama , H., Easterday , R. L., Chang, H. C., & Lane, M. D. (1966) J. Biol. Chem. 241, 2405-2412] but essentially consistent with the current stepwise mechanism [O'Leary, M. H., Rife , J. E., & Slater , J. D. (1981) Biochemistry 20, 7308-7314].
    [Abstract] [Full Text] [Related] [New Search]