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On the rate of F 1 ‐ATPase turnover during ATP hydrolysis by the single catalytic site Evidence that hydrolysis with a slow rate of product release does not occur at the alternating active site
Author(s) -
Milgrom Ya.M.,
Murataliev M.B.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80186-2
Subject(s) - atp hydrolysis , hydrolysis , chemistry , atpase , catalysis , enzyme , turnover number , reaction rate constant , kinetics , biochemistry , medicinal chemistry , physics , quantum mechanics
Under conditions of molar excess of enzyme, isolated F 1 ‐ATPase from beef heart mitochondria catalyses ATP hydrolysis biphasically. The rate constants for product release are ∼10 −1 and 10 −4 −10 −3 s −1 , respectively. The slow phase of ATP hydrolysis is insensitive to EDTA. [γ‐ 32 P]ATP splitting in the slow phase cannot be chased from the enzyme during several catalytic turnovers. It follows from these results that the slow single‐site hydrolysis of ATP ( k cat ∼10 −4 s −1 ), initially observed by Grubmeyer et al. [(1982) J. Biol. Chem. 257, 12092–12100], is not carried out by the normal catalytic site. In contrast, the phase of rapid ATP hydrolysis ( k cat ∼10 −1 s −1 ) is completely prevented by EDTA and is believed to be the normal function of the normal catalytic site of F 1 ‐ATPase.