Distribution of flux control among the enzymes of mitochondrial oxidative phosphorylation in calcium-activated saponin-skinned rat musculus soleus fibers

Eur J Biochem. 1995 Jun 1;230(2):549-54. doi: 10.1111/j.1432-1033.1995.0549h.x.


Metabolic control analysis was applied to describe the control of mitochondrial oxidative phosphorylation in calcium (approximately 2 microM free calcium) activated saponin-skinned rat musculus soleus fibers oxidizing glutamate and malate. Under these circumstances approximately 80% of mitochondrial active-state respiration was reached due to the activation of ATP turnover by actomyosin ATPase. The flux control coefficients of H(+)-ATPase, adenine-nucleotide translocase, phosphate transporter, NADH:ubiquinone oxidoreductase and cytochrome-c oxidase were determined to be equal to 0.16 +/- 0.08 (n = 6), 0.34 +/- 0.12 (n = 5), 0.08 +/- 0.03 (n = 5), 0.01 +/- 0.006 (n = 4) and 0.09 +/- 0.03 (n = 3) using inhibitor titrations with the specific inhibitors oligomycin, carboxyatractyloside, mersalyl, rotenone and cyanide, respectively, and applying non-linear regression of the entire titration curve. The flux control coefficient of actomyosin ATPase was determined with vanadate to be equal to 0.50 +/- 0.09 (n = 6), measuring independently the vanadate-caused inhibition of fiber respiration and ATP-splitting activity. In contrast to results with isolated rat skeletal muscle mitochondria reconstituted with soluble F1-ATPase the decrease in phosphate concentration from 10 mM to 1 mM only slightly affected the distribution of flux control coefficients. This difference is caused by different kinetic properties of soluble F1-ATPase and actomyosin ATPase. Therefore, phosphate seems to be in skeletal muscle in vivo only a modest modulator of control of oxidative phosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphate / metabolism
  • Animals
  • Calcium / metabolism*
  • Enzyme Activation
  • In Vitro Techniques
  • Male
  • Mitochondria, Muscle / enzymology*
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / enzymology
  • Muscle, Skeletal / physiology*
  • Oxidative Phosphorylation
  • Rats
  • Rats, Wistar
  • Saponins / pharmacology


  • Saponins
  • Adenosine Diphosphate
  • Adenosine Triphosphate
  • Calcium