Mitochondrial respiration and membrane potential are regulated by the allosteric ATP-inhibition of cytochrome c oxidase

作者：Ramzan Rabia; Staniek Katrin; Kadenbach Bernhard^*; Vogt Sebastian

来源：Biochimica et Biophysica Acta-Bioenergetics, 2010, 1797(8): 1672-1680.

DOI：10.1016/j.bbabio.2010.06.005

• Cytochrome c oxidase
• Regulation of respiration
• Mitochondrial membrane potential
• ATP/ADP ratio
• Respiratory control
• Tetraphenyl phosphonium electrode

This paper describes the problems of measuring the allosteric ATP-inhibition of cytochrome c oxidase (CcO) in isolated mitochondria. Only by using the ATP-regenerating system phosphoenolpyruvate and pyruvate kinase full ATP-inhibition of CcO could be demonstrated by kinetic measurements. The mechanism was proposed to keep the mitochondrial membrane potential (Delta Psi(m)) in living cells and tissues at low values (100-140 mV), when the matrix ATP/ADP ratios are high. In contrast, high Delta Psi(m) values (180-220 mV) are generally measured in isolated mitochondria. By using a tetraphenyl phosphonium electrode we observed in isolated rat liver mitochondria with glutamate plus malate as substrates a reversible decrease of Delta Psi(m) from 233 to 123 mV after addition of phosphoenolpyruvate and pyruvate kinase. The decrease of Delta Psi(m) is explained by reversal of the gluconeogenetic enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase yielding ATP and GTP, thus increasing the matrix ATP/ADP ratio. With rat heart mitochondria, which lack these enzymes, no decrease of Delta Psi(m) was found. From the data we conclude that high matrix ATP/ADP ratios keep Delta Psi(m) at low values by the allosteric ATP-inhibition of CcO, thus preventing the generation of reactive oxygen species which could generate degenerative diseases. It is proposed that respiration in living eukaryotic organisms is normally controlled by the Delta Psi(m)-independent "allosteric ATP-inhibition of CcO." Only when the allosteric ATP-inhibition is switched off under stress, respiration is regulated by "respiratory control," based on Delta Psi(m) according to the Mitchell Theory.

• 出版日期2010-9