Reducing power of respiratory substrates and bioluminescence in photobacterium phosphoreum and vibrio harveyi

in Campbell, A. K.; Kricka, L. J.; Stanley, P. E. (Eds.) Bioluminescence and Chemiluminescence : fundamentals and applied aspects (1994)

Effect of aspartate and glutamate on the oxoglutarate carrier investigated in rat heart mitochondria and inverted submitochondrial vesicles.

in Biochimica et Biophysica Acta-Bioenergetics (1994), 1185

Interaction of glutamate and aspartate with the oxoglutarate carrier was investigated in rat heart mitochondria or inverted submitochondrial particles. With mitochondria, glutamate and aspartate had no ... [more ▼]

Interaction of glutamate and aspartate with the oxoglutarate carrier was investigated in rat heart mitochondria or inverted submitochondrial particles. With mitochondria, glutamate and aspartate had no effect on the initial rate of oxoglutarate or malate uptake. With inverted submitochondrial vesicles, binding experiments indicated that aspartate bound to the oxoglutarate carrier on its matricial face and increased the affinity of the substrate binding site for malate but did not change the affinity for oxoglutarate. Glutamate had no effect on both substrate bindings. The dissociation constants of the binary substrate-carrier complexes on the matricial side were determined (1.28 +/- 0.15 mM for oxoglutarate and 2.22 +/- 0.26 mM for malate). These values, compared with those obtained previously on the cytosolic side of intact mitochondria, confirmed the asymmetry of the carrier in the native membrane (higher affinities on the cytosolic face). It is concluded that (1) aspartate and glutamate are not cytosolic effectors of the oxoglutarate carrier, (2) matricial aspartate is a positive effector of the binding of malate on the matricial side of the oxoglutarate carrier, and (3) such a characteristic may play a role in the regulation of the oxoglutarate carrier. Thus, it may be emphasized that (1) this observation is the first clear evidence of a well-defined 'sophisticated regulation' (allosteric) of a mitochondrial metabolite carrier, and (2) this regulation of the oxoglutarate carrier may have important consequences on the efficiency of reducing equivalent import in the matrix space by the malate-aspartate shuttle. [less ▲]

Effect of pH on CN-resistant respiratory activity and it's regulation on Vigna uniguiculata mitochondria

in Moller, I. M.; Gardestrom, P.; Glimelius, K. (Eds.) et al Plant mitochondria : from gene to function (1993)

Biochemical, bioenergetic and ultrastructural survey of the adaptations induced in a skeletal muscle by a chronic electrical stimulation and its cessation

in Carraro, U.; Salmons, S. (Eds.) Basic and applied myology : Perspectives for the 90's (1992)

Study of a new presumed mitochondrial carrier, the product of the yeast RIM 2 gene

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1992), 100

Kinetic study of the aspartate/glutamate carrier in intact rat heart mitochondria and comparison with a reconstituted system.

in Biochimica et Biophysica Acta-Bioenergetics (1991), 1058

The homologous exchange of external [14C] aspartate/internal aspartate catalyzed by the aspartate/glutamate carrier of rat heart mitochondria was investigated using aspartate-loaded, glutamate-depleted ... [more ▼]

The homologous exchange of external [14C] aspartate/internal aspartate catalyzed by the aspartate/glutamate carrier of rat heart mitochondria was investigated using aspartate-loaded, glutamate-depleted mitochondria. An inhibitor-stop technique was developed for kinetic studies by applying pyridoxal phosphate. Direct initial rate determinations from the linear phase of [14C] aspartate uptake were insufficiently accurate at high external and/or low internal substrate concentrations. Therefore, the full time-course of [14C] aspartate uptake until reaching isotope equilibrium was fitted by a single exponential function and was used to calculate reliable initial steady-state rates. This method was applied in bisubstrate analyses of the antiport reaction for different external and internal aspartate concentrations. The kinetic patterns obtained in double reciprocal plots showed straight lines converging on the abscissa. This result is consistent with a sequential antiport mechanism. It implies the existence of a catalytic ternary complex that is formed by the translocator and substrate molecules bound from both sides of the membrane. The Km values for aspartate were clearly different for the external and the internal sides of the membrane, 216 +/- 23 microM and 2.4 +/- 0.5 mM, respectively. These values indicated a definite transmembrane asymmetry of the carrier. The same asymmetry became evident when investigating the isolated protein from bovine heart mitochondria after reconstitution into liposomes. In this case the Km values for external and internal aspartate were determined to be 123 +/- 11 microM and 2.8 +/- 0.6 mM, respectively. This comparison demonstrates a right-side out orientation of the carrier after insertion into liposomal membranes. The sequential transport mechanism of the aspartate/glutamate carrier, elucidated both in proteoliposomes and in mitochondria, also seems to be a common characteristic of other mitochondrial antiport carriers [less ▲]

Iron status in runners of various running specialities

in Archives Internationales de Physiologie et de Biochimie (1990), 98

Induction and Characterization of Mitochondrial DNA Mutants in Chlamydomonas Reinhardtii

in Journal of Cell Biology (1989), 108(4), 1221-6

In addition to lethal minute colony mutations which correspond to loss of mitochondrial DNA, acriflavin induces in Chlamydomonas reinhardtii a low percentage of cells that grow in the light but do not ... [more ▼]

In addition to lethal minute colony mutations which correspond to loss of mitochondrial DNA, acriflavin induces in Chlamydomonas reinhardtii a low percentage of cells that grow in the light but do not divide under heterotrophic conditions. Two such obligate photoautotrophic mutants were shown to lack the cyanide-sensitive cytochrome pathway of the respiration and to have a reduced cytochrome c oxidase activity. In crosses to wild type, the mutations are transmitted almost exclusively from the mating type minus parent. A same pattern of inheritance is seen for the mitochondrial DNA in crosses between the two interfertile species C. reinhardtii and Chlamydomonas smithii. Both mutants have a deletion in the region of the mitochondrial DNA containing the apocytochrome b gene and possibly the unidentified URFx gene. [less ▲]

Kinetic mechanism of the adenylic and the oxoglutaruc carriers : a comparison

in Azzi, A.; Nalecz, M. J.; Wojtczak, L. (Eds.) Anion carriers of mitochondrial membranes (1989)

Spontaneous modification of the oxoglutarate translocator in vivo.

in European Journal of Biochemistry (1984), 142