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REACTION MECHANISM OF PYROPHOSPHATE‐DEPENDENT PHOSPHOFRUCTOKINASE FROM PINEAPPLE LEAVES
Author(s) -
CHO YONGKWEON
Publication year - 1993
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1993.tb00862.x
Subject(s) - phosphofructokinase , pyrophosphate , chemistry , dissociation (chemistry) , fructose , fructose 2,6 bisphosphate , phosphate , catalysis , enzyme , product inhibition , dissociation constant , stereochemistry , medicinal chemistry , biochemistry , organic chemistry , non competitive inhibition , glycolysis , receptor
Data obtained from initial velocity, product inhibition and dead‐end inhibition patterns indicate that the pyrophosphate‐dependent phosphofructokinase from pineapple leaves has a rapid equilibrium random mechanism with E:F6P:MgPP i and E:MgPP i :FBP dead‐end complexes. The pH dependence of enzyme‐reactant dissociation constants suggests that phosphates of F6P (fructose 6‐phosphate), FBP (fructose 1,6‐bisphosphate), P i and PP i must be completely ionized and the lysine is present in the vicinity of the 1‐ and 6‐phosphates of the sugar phosphate and bisphosphate. The pH dependence of kinetic parameters suggests that the enzyme catalyzes the reaction via general acid‐base catalysis with the use of a proton shuttle. The base is required to be unprotonated in both reaction directions.