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Fru 2,6‐P2 and citrate: Intracellular distribution in citrus tissues and effect on grapefruit leaf PFP.
Author(s) -
Van Praag Esther,
Gonzalez Pedro,
Brune Andreas,
Goren Raphael,
Zehavi Uri,
Echeverria Ed
Publication year - 1998
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549800201122
Subject(s) - grapefruit juice , intracellular , chemistry , cytosol , fructose , metabolite , biochemistry , glycolysis , citric acid , food science , metabolism , enzyme , biology , pharmacokinetics , pharmacology
Grapefruit leaf PFP was studied for its activation by fructose 2,6‐bisphosphate (Fru 2,6‐P2) in the forward and reverse reactions. In the glycolytic reaction, a Ka of 4.0±0.12 nM was obtained. This constant is affected by the presence of increasing concentrations of citrate (1, 5 and 20 mM) with a Ka(citrate) of 4.5±0.09, 6.9±0.05 and 38.2±1.4 respectively. The inhibition mode of citrate is competitive with Fru 2,6‐P2, but non‐linear in relation of increasing concentrations of the inhibitor. The intracellular distribution and concentration of the key regulatory metabolite Fru 2,6‐P2 was further investigated in citrus leaves and juice cells. Fru 2,6‐P2 was only found in the cytosol of juice cells. Fru 2,6‐P2 was detected under both conditions with higher concentrations found under aerobiosis.