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  • Rhodospirillum rubrum  (1)
  • membrane potential  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Energy-transducing nicotinamide nucleotide transhydrogenase: Nucleotide sequences of the genes and predicted amino acid sequences of the subunits of the enzyme fromRhodospirillum rubrum (1994)
    Springer
    Journal of bioenergetics and biomembranes 26 (1994), S. 435-445 
    Details
    ISSN: 1573-6881
    Keywords: Nicotinamide nucleotide transhydrogenase ; subunits ; amino acid sequence ; Rhodospirillum rubrum ; proton pump
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Based on the amino acid sequence of the N-terminus of the soluble subunit of theRhodospirillum rubrum nicotinamide nucleotide transhydrogenase, two oligonucleotide primers were synthesized and used to amplify the corresponding DNA segment (110 base pairs) by the polymerase chain reaction. Using this PCR product as a probe, one clone with the insert of 6.4kbp was isolated from a genomic library ofR. rubrum and sequenced. This sequence contained three open reading frames, constituting the genesnntA1, nntA2, andnntB of theR. rubrum transhydrogenase operon. The polypeptides encoded by these genes were designated α1, α2, and β, respectively, and are considered to be the subunits of theR. rubrum transhydrogenase. The predicted amino acid sequence of the α1 subunit (384 residues; molecular weight 40276) has considerable sequence similarity to the α subunit of theEscherichia coli and the N-terminal 43-kDa segment of the bovine transhydrogenases. Like the latter, it has a βαβ fold in the corresponding region, and the purified, soluble α 1 subunit cross-reacts with antibody to the bovine N-terminal 43-kDa fragment. The predicted amino acid sequence of the β subunit of theR. rubrum transhydrogenase (464 residues; molecular weight 47808) has extensive sequence identity with the β subunit of theE. coli and the corresponding C-terminal sequence of the bovine transhydrogenases. The chromatophores ofR. rubrum contain a 48-kDa polypeptide, which cross-reacts with antibody to the C-terminal 20-kDa fragment of the bovine transhydrogenase. The predicted amino acid sequence of the α2 subunit of theR. rubrum enzyme (139 residues; molecular weight 14888) has considerable sequence identity in its C-terminal half to the corresponding segments of the bovine and the α subunit of theE. coli transhydrogenases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00762784
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  • 2
    Electronic Resource
    Electronic Resource
    Role of energy in oxidative phosphorylation (1988)
    Springer
    Journal of bioenergetics and biomembranes 20 (1988), S. 481-502 
    Details
    ISSN: 1573-6881
    Keywords: Oxidative phosphorylation ; energy communication ; affinity change ; kinetic modalities ; membrane potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract This article reviews the current status of information regarding the role of energy in the process of oxidative phosphorylation by mitochondria. The available data suggest that in submitochondrial particles (SMP) energy is utilized for the binding of ADP and Pi and for the release of ATP bound at the catalytic sites of F1-ATPase. The process of ATP synthesis on the surface of F1 from F1-bound ADP and Pi appears to be associated with negligible free energy change. The rate of energy production by the respiratory chain modulates the kinetics of ATP synthesis between a lowK m (for ADP and Pi)-lowV max mode and a highK m -highV max mode. TheK m extremes for ADP are 2–3 µM and 120–150 µM, andV max for ATP synthesis at high rates of energy production by bovine-heart SMP is about 440 s−1 (mole F1)−1 at 30°C, which corresponds to 11 µmol ATP (min · mg of protein)−1. The interaction of dicyclohexylcarbodiimide (DCCD) or oligomycin at the proteolipid (subunitc) of the membrane sector (F0) of the ATP synthase complex alters the mode of ATP binding at the catalytic sites of F1, probably to one of lower affinity. It has been suggested that protonic energy might be conveyed to the catalytic sites of F1 in an analogous manner, i.e., via conformation changes in the ATP synthase complex initiated by proton-induced alterations in the structure of the DCCD-binding proteolipid. Finally, the relationship between the steady-state membrane potential (Δψ) and the rates of electron transfer and ATP synthesis has been discussed. It has been shown, in agreement with the delocalized chemiosmotic mechanism, that under appropriate conditions Δψ is exquisitely sensitive to changes in the rates of energy production and consumption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00762205
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    Paper (German National Licenses)
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