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An ATP dependence of mitochondrial F 1 ‐ATPase inactivation by the natural inhibitor protein agrees with the alternating‐site binding‐change mechanism
Author(s) -
Milgrom Ya.M.
Publication year - 1989
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(89)80283-2
Subject(s) - inhibitor protein , atpase , mitochondrion , binding site , conformational change , chemistry , biochemistry , atp synthase , mechanism of action , active site , biophysics , enzyme , stereochemistry , biology , in vitro
The rate of inactivation of F 1 ‐ATPase, isolated from beef heart mitochondria, by the active acidic form of the natural inhibitor protein depends on the ATP concentration. An increase in concentration of ATP to ∼ 20 μM leads to a decrease in that of the inhibitor protein inducing 50% inhibition of the F 1 ‐ATPase during 5 s preincubation ( C 50 ); further increase in ATP concentration to 1 mM causes little, if any, change in C 50 . However, the C 50 values show a rise at ATP concentrations higher than 1 mM. This ATP dependence of the inhibitor action may be in agreement with a version of the alternating‐site binding‐change mechanism, which assumes that the two‐site catalytic cycle intermediates possessing (i) the products (ADP + P i ) bound in the low‐affinity state at one of the active sites and (ii) an ATP molecule at the other active site are the targets for the acidic form of the inhibitor protein.