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  • 1
    Electronic Resource
    Electronic Resource
    Interaction of high-affinity nucleotide binding sites in mitochondrial ATP synthesis and hydrolysis (1982)
    Springer
    Journal of bioenergetics and biomembranes 14 (1982), S. 479-498 
    Details
    ISSN: 1573-6881
    Keywords: Oxidative phosphorylation ; F1-ATPase ; nucleotide binding sites ; cooperativity ; nucleotide analogs ; fluorescence ; mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The present study contributes to the problem of the dynamic structure of mitochondrial F1-ATPase and the functional interrelation of so-called tight nucleotide binding sites. Nucleotide analogs are used as a tool to differentiate two distinct functional states of the membrane-bound enzyme, proposed to reflect corresponding conformational states; they reveal F1-ATPase as a “dual-state” enzyme: ATP-synthetase, and ATP-hydrolase. The analogs used are 3′-naphthoyl esters of AD(T)P, and 2′(3′)-O-trinitrophenyl ethers of AD(T)P. Both types of analogs act inversely to each other with respect to their relative effects on oxidative phosphorylation and on ATPase in submitochondrial vesicles. The respective ratios ofK i versus both processes are 250/1 compared to 1/170. It is also shown that in the presence of the inhibitory 3′-esters oxidative phosphorylation deviates from linear kinetics and that these inhibitors induce a lag time of oxidative phosphorylation depending on the initial pattern of nucleotides available to energized submitochondrial vesicles. The duration of the lag time coincides with the time course of displacement of the analog from a tight binding site. The conclusions of the study are: (a) the catalytic sites of F1-ATP-synthetase are not operating independently from each other; they rather interact in a cooperative manner; (b) F1-ATPase as a “dual-state” enzyme exhibits highly selective responses to tight binding of nucleotides or analogs in its “energized” (membrane-bound) state versus its “nonenergized” state, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00743073
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  • 2
    Electronic Resource
    Electronic Resource
    Studies of the Electron Transport Chain of the Euryarcheon Halobacterium salinarum: Indications for a Type II NADH Dehydrogenase and a Complex III Analog (1998)
    Springer
    Journal of bioenergetics and biomembranes 30 (1998), S. 443-453 
    Details
    ISSN: 1573-6881
    Keywords: Archea ; inhibitors ; NADH dehydrogenase ; complex III ; cytochromes ; Rieske iron–sulfur cluster ; terminal oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The components involved in the respiratory system of the euryarcheon Halobacterium salinarum were investigated by spectroscopic and polarographic techniques. Previous results about the cytochrome composition could be verified. However, under low oxygen tension, the expression of a d-type cytochrome was detected. Membranes exerted an NADH– and succinate–cytochrome-c oxidoreductase as well as an NADH and succinate oxidase activity. These activities could be blocked by the following inhibitors: 7-jodocarboxylic acid, giving evidence for the presence of a type II NADH dehydrogenase, antimycin A, and myxothiazol, indicating the presence of a complex III analog, and the typical succinate dehydrogenase (SDH) and terminal oxidase inhibitors. Complex I inhibitors like rotenone and annonine were inactive, clearly excluding the presence of a coupled NADH dehydrogenase. In addition, no [Fe-S] resonances in the region of the NADH dehydrogenase (NDH) clusters could be observed after NADH addition. One of the terminal oxidases could be shown to act as a cytochrome-c oxidase with a K m value of 37 μM and an activation energy of 23.7 kJ/mol. The relative molecular mass of the endogenous c-type cytochrome could be determined as 14.1 kD. The complex III analog could be enriched after detergent extraction with Triton X-100 and hydroxylapatite (HTP) chromatography. The partially purified complex contained a Rieske iron–sulfur cluster, b- and c-type cytochromes, and was catalytically active in the decylubiquinone–cytochrome-c oxidoreductase assay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020538129400
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    Paper (German National Licenses)
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