Once again about the functional coupling between mitochondrial creatine kinase and adenine nucleotide translocase |
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Authors: | Lipskaya T Yu Savchenko M S |
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Institution: | (1) Department of Biochemistry, School of Biology, Lomonosov Moscow State University, Moscow, 119992, Russia |
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Abstract: | The synthesis of creatine phosphate (CP) by mitochondrial creatine kinase during oxidative phosphorylation was terminated when the mass action ratio of the creatine kinase reaction = ADP]·CP]ATP]·Cr] became equal to the apparent equilibrium constant (K
eq
app) of this reaction. Subsequent excess of over the K
eq
app was due to an increase in the ADP concentration in the medium. A comparable increase in the ADP concentration also occurred in the absence of creatine (Cr) in the incubation medium. Increase in the ADP concentration was shown to be associated with a decrease in the rate of oxidative phosphorylation and with a relative increase in the ATPase activity of mitochondria during the incubation. A low concentration of ADP (<30 M) and relatively high concentrations (1-6 mM) of other components of the creatine kinase reaction prevented the detection of the reverse reaction within 10 min after exceeded the K
eq
app, but the reverse reaction became evident on more prolonged incubation. The reverse reaction was accompanied by a further increase in . Low ADP concentration in the medium was also responsible for the lack of an immediate conversion of the excess creatine phosphate added although > K
eq
app. The findings are concluded to be in contradiction with the concept of microcompartment formation between mitochondrial creatine kinase and adenine nucleotide translocase. |
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Keywords: | mitochondrial creatine kinase physiological role adenine nucleotide translocase functional coupling |
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