Induction of Pyrophosphate-Dependent Phosphofructokinase in Watermelon (Citrullus lanatus) Cotyledons Coincides with Insufficient Cytosolic D-Fructose-1,6-Bisphosphate 1-Phosphohydrolase to Sustain Gluconeogenesis
Author(s) -
AnnaMaria Botha,
Frederik C. Botha
Publication year - 1993
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.101.4.1385
Subject(s) - fructose 1,6 bisphosphatase , fructose 2,6 bisphosphate , citrullus lanatus , phosphofructokinase , cytosol , biochemistry , pyrophosphate , gluconeogenesis , fructose , flux (metallurgy) , glycolysis , phosphofructokinase 2 , chemistry , biology , enzyme , botany , organic chemistry
During germination of Citrullus lanatus, pyrophosphate-dependent phosphofructokinase (PFP) activity is induced. The peak of PFP activity coincides with the maximum gluconeogenic flux and high fructose-2,6-bisphosphate (Fru-2,6-P2) concentrations. Determination of cytosolic fructose-1,6 bisphosphatase (FBPase) activity in crude extracts is unreliable because of the high PFP activity. The FBPase activity, after correction for the contaminating PFP, is only one-third of the PFP activity. Purified cytosolic FBPase is inhibited by Fru-2,6-P2. The low cytosolic FBPase activity and high Fru-2,6-P2 most probably result in inadequate in vivo activity to catalyze the observed gluconeogenic flux. The total PFP activity is sufficient to catalyze the required carbon flux.
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