Abstract
The problem of obtaining very early ratios for the H+/O stoichiometry accompanying succinate oxidation by rat liver mitochondria was attacked using new techniques for direct measurement rather than extrapolations based on data obtained after mixing and the recovery of the electrode from initial injection of O2. Respiration was quickly initiated in a thoroughly mixed O2-containing suspension of mitochondria under a CO atmosphere by photolysis of the CO-cytochrome c oxidase complex-. Fast responding O2 and pH electrodes were used to collect data every 10 ms. The response time for each electrode was experimentally measured in each experiment and suitable corrections for electrode relaxations were made. With uncorrected data obtained after 0.8 s, the extrapolation back to zero time on the basis of single-exponential curve fitting confirmed values close to 8.0 as previously reported (Costa et al., 1984). The data directly obtained, however, indicate an initial burst in H+/O ratio that peaked to values of approximately 20 to 30 prior to 50 ms and which was no longer evident after 0.3 s. Newer information and considerations that place all extrapolation methods in question are discussed.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Costa L. E., Reynafarje B., Lehninger A. L. Stoichiometry of mitochondrial H+ translocation coupled to succinate oxidation at level flow. J Biol Chem. 1984 Apr 25;259(8):4802–4811. [PubMed] [Google Scholar]
- Hendler R. W., Setty O. H., Shrager R. I., Songco D. C., Friauf W. S. Instrumentation and procedures for real time measurements of proton motive force, membrane potential, delta pH, proton extrusion, and oxygen uptake in respiring cells and vesicles. Rev Sci Instrum. 1983 Dec;54(12):1749–1755. doi: 10.1063/1.1137326. [DOI] [PubMed] [Google Scholar]
- Pedersen P. L., Greenawalt J. W., Reynafarje B., Hullihen J., Decker G. L., Soper J. W., Bustamente E. Preparation and characterization of mitochondria and submitochondrial particles of rat liver and liver-derived tissues. Methods Cell Biol. 1978;20:411–481. doi: 10.1016/s0091-679x(08)62030-0. [DOI] [PubMed] [Google Scholar]
- Reynafarje B., Alexandre A., Davies P., Lehninger A. L. Proton translocation stoichiometry of cytochrome oxidase: use of a fast-responding oxygen electrode. Proc Natl Acad Sci U S A. 1982 Dec;79(23):7218–7222. doi: 10.1073/pnas.79.23.7218. [DOI] [PMC free article] [PubMed] [Google Scholar]