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Nucleotide/H + ‐dependent change in Mg 2+ affinity at the ATPase inhibitory site of the mitochondrial F 1 ‐F 0 ATP synthase
Author(s) -
Bulygin V.V.,
Syroeshkin A.V.,
Vinogradov A.D.
Publication year - 1993
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(93)80991-3
Subject(s) - atpase , nucleotide , binding site , chemistry , atp synthase , inhibitory postsynaptic potential , atp hydrolysis , stoichiometry , stereochemistry , enzyme , biochemistry , biology , organic chemistry , neuroscience , gene
The interactions between ADP and Mg 2+ that result in the slowly reversible inhibition of the mitochondrial F 1 ‐F 0 ATPase were studied. The K i for the inhibitory Mg 2+ is shown to be strongly dependent on the occupation of the nucleotide‐binding sites. The inhibitory binding site for Mg 2+ is not seen unless a stoichiometric amount of ADP is added [Biochem. J. 276 (1991) 149‐156]; it appears ( K i = 2.10 −6 M) in the presence of stoichiometric ADP and the affinity for inhibitory Mg 2+ decreases to a K i , value of 7.10 −5 M when the second nueleotide binding site with k d = 5.10 −6 M is loaded with ADP. The binding of the inhibitory Mg 2+ is competitively inhibited by H + ions within the pH interval 6.8–8.2. The nucleotide‐dependent affinity transition of the Mg 2+ ‐specific site suggests that H + /Mg 2+ exchange may play an important role in the catalytic mechanism of ATP synthesis/hydrolysis at the active site(s) of F 1 ‐F 0 ATP synthase.