Wisniewski 1995 Eur J Biochem
|Wisniewski E, Gellerich FN, Kunz WS (1995) Distribution of flux control among the enzymes of mitochondrial oxidative phosphorylation in calcium-activated saponin-skinned rat musculus soleus fibers. Eur J Biochem 230:549-54.|
Abstract: Metabolic control analysis was applied to describe the control of mitochondrial oxidative phosphorylation in calcium (approximately 2 pM free calcium) activated saponin-skinned rat musculus soleus fibers oxidizing glutamate and malate. Under these circumstances approximately 80 % of mitochondrial activestate 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 2 0.08 (n = 6), 0.34? 0.12 (n = 5), 0.08 2 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 F,-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 F,-ATPase and actomyosin ATPase. Therefore, phosphate seems to be in skeletal muscle in vivo only a modest modulator of control of oxidative phosphorylation.
• Keywords: Skinned muscle fibers, Flux control, Oxidative phosphorylation
Organism: Rat Tissue;cell: Skeletal muscle Preparation: Permeabilized tissue