If no protons or other ions move exchanging citrate

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Unformatted text preview: charge of -2. If no protons or other ions move, exchanging citrate for malate moves a net charge of -1 from the matrix to the cytosol. Citrate efflux thus would be favored by the electrical potential difference if the matrix is negatively charged relative to the cytosol. Proton efflux coupled to electron transport creates a potential difference in respiring mitochondria, and flow of protons back into the matrix through the ATP synthase (FoF1) drives formation of ATP. In the present experiments, respiration is blocked by antimycin A and KCN, but the ATP synthase would still be functional. Hydrolysis of ATP (reversal of the reaction usually catalyzed by the synthase) moves protons out of the matrix, creating an electrical potential difference that would favor citrate/malate exchange. Another possibility would be that citrate/malate exchange can be driven directly by ATP. By collapsing the membrane potential, FCCP would facilitate ATP hydrolysis and might lower the concentration of ATP below the level required for a...
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This note was uploaded on 02/02/2010 for the course BIOCHEMIST Biochem 44 taught by Professor Parson,young during the Winter '10 term at University of Washington.

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