Oxidation of cytochrome c2 and of cytochrome c by reaction centers of Rhodospirillum rubrum and Rhodobacter sphaeroides. The effect of ionic strength and of lysine modification on oxidation rates

Wal, H. N. Van Der; Grondelle, Rienk van; Millett, Francis; Knaff, David B.

doi:10.1016/0005-2728(87)90100-9

Cited by 16 publications

(10 citation statements)

References 22 publications

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“…As already reported (Van Grondelle et al, 1976;Rickie & Cusanovich, 1979;Van der Wal et al, 1987), cyt c2 displays a much lower affinity for the reaction center in Rs. rubrum than in Rb.…”

Section: Resultssupporting

confidence: 77%

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Electron transfer between primary and secondary donors in Rhodospirillum rubrum: evidence for a dimeric association of reaction centers

Joliot

Vermeglio²,

Joliot³

1990

Biochemistry

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Light-induced oxidation of the primary electron donor P and of the secondary donor cytochrome c2 was studied in whole cells of Rhodospirillum rubrum in the presence of myxothiazole to slow down their reduction. 1. The primary and secondary electron donors are close to thermodynamic equilibrium during continuous illumination when the rate of the electron transfer is light-limited. This implies a long-range thermodynamic equilibration involving the diffusible cytochrome c2. A different behavior is observed with Rhodobacter sphaeroides R26 whole cells, in which the cytochrome c2 remains trapped within a supercomplex including reaction centers and the cytochrome b/c complex [Joliot, P., et al. (1989) Biochim. Biophys. Acta 975, 336-345]. 2. Under weak flash excitation, the reduction kinetics of the photooxidized primary donor are nearly exponential with a half-time in the hundred microseconds time range. 3. Under strong flash excitation, the reduction of the photooxidized primary donor follows a second-order kinetics. About half of the photooxidized primary donor is reduced in a few milliseconds while the remainder stays oxidized for hundreds of milliseconds despite an excess of secondary donors in their reduced form. The flash intensity dependence of the amplitude of the slow phase of P+ reduction is proportional to the square of the fraction of reaction centers that have undergone a charge separation.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…As already reported (Van Grondelle et al, 1976;Rickie & Cusanovich, 1979;Van der Wal et al, 1987), cyt c2 displays a much lower affinity for the reaction center in Rs. rubrum than in Rb.…”

Section: Resultssupporting

confidence: 77%

“…In experiments performed with purified cyt c2 and reaction centers from Rs. rubrum, the oxidation kinetics were found to be second order and presented no fast phase at any ionic strength (Rickie & Cusanovich, 1979; Van der Wal et al, 1987). This strongly suggests that no tightly bound cyt c2 is present prior to the charge separation reaction.…”

mentioning

confidence: 90%

Electron transfer between primary and secondary donors in Rhodospirillum rubrum: evidence for a dimeric association of reaction centers

Joliot

Vermeglio²,

Joliot³

1990

Biochemistry

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“…Most early efforts to fit such data simply treated the protein as a monopole of adjustable charge; the best-fit charge was assumed to be that of the active site. Cytochrome c has also been extensively studied by specific functionalization of single residues; these experiments have mapped the residues which appear to be most important in cytochrome c-partner interactions for the reactions of cytochrome c with a variety of reaction partners (Margoliash and Bosshard, 1983;Concar et al, 1986;Bosshard et al, 1987;van der Wal et al, 1987;Bosshard and Ritzmann, 1988).…”

Section: Introductionmentioning

confidence: 99%

Electrostatic and steric control of electron self-exchange in cytochromes c, c551, and b5

Dixon

Hong

Woehler

1989

Biophysical Journal

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The ionic strength dependence of the electron self-exchange rate constants of cytochromes c, c551, and b5 has been analyzed in terms of a monopole-dipole formalism (van Leeuwen, J.W. 1983. Biochim. Biophys. Acta. 743:408-421). The dipole moments of the reduced and oxidized forms of Ps. aeruginosa cytochrome c551 are 190 and 210 D, respectively (calculated from the crystal structure). The projections of these on the vector from the center of mass through the exposed heme edge are 120 and 150 D. For cytochrome b5, the dipole moments calculated from the crystal structure are 500 and 460 D for the reduced and oxidized protein; the projections of these dipole moments through the exposed heme edge are -330 and -280 D. A fit of the ionic strength dependence of the electron self-exchange rate constants gives -280 (reduced) and -250 (oxidized) D for the center of mass to heme edge vector. The self-exchange rate constants extrapolated to infinite ionic strength of cytochrome c, c551, and b5 are 5.1 x 10(5), 2 x 10(7), and 3.7 x 10(5) M-1 s-1, respectively. The extension of the monopole-dipole approach to other cytochrome-cytochrome electron transfer reactions is discussed. The control of electron transfer by the size and shape of the protein is investigated using a model which accounts for the distance of the heme from each of the surface atoms of the protein. These calculations indicate that the difference between the electrostatically corrected self-exchange rate constants of cytochromes c and c551 is due only in part to the different sizes and heme exposures of the two proteins.

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“…rubrum and Rb. sphaeroides, only slow second-order kinetics were observed (Rickie & Cusanovich, 1979; Van der Wal et al, 1987;Long et al, 1989). These results indicate that the cytochrome binding may vary among different species.…”

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confidence: 98%

Interaction between Cytochrome c2 and Reaction Centers from Purple Bacteria

Wang

Williams

et al. 1994

Biochemistry

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The kinetics of electron transfer of cytochrome c2 from Rhodobacter sphaeroides, Rhodobacter capsulatus, and Rhodospirillum centenum to reaction centers from Rb. sphaeroides and Rb. capsulatus have been measured. Observed in the kinetics of decay of the oxidized donor are a rapid first-order rate and one or more slower rates that are due to diffusion-limited complex formation. For reaction centers from Rb. sphaeroides, the fast component had time constants of 1.0 and 0.5 microsecond for cytochrome c2 from Rb. sphaeroides and Rb. capsulatus, respectively, but only a slow component was observed for cytochrome c2 from Rs. centenum. For reaction centers from Rb. capsulatus, the kinetics from all three cytochromes had a fast component with time constants of 1.0, 0.7, and 1.9 microseconds for cytochrome c2 from Rb. sphaeroides, Rb. capsulatus, and Rs. centenum, respectively, although the dissociation constant for cytochrome c2 from Rs. centenum was approximately 20 times larger than that of the other cytochromes. The observation of the fast component for cytochrome c2 from Rs. centenum in reaction centers from Rb. capsulatus but not Rb. sphaeroides demonstrates that the binding interactions for the two reaction centers differ, and the involvement of amino acid residues in the binding is discussed. The kinetics of electron transfer from cytochrome c2 to reaction centers of Rb. sphaeroides from wild type and three mutant strains that have altered carboxyl-terminal regions of the M subunit of the reaction center have also been measured. For cytochrome c2 from Rb. sphaeroides, the kinetics are very similar between the mutants and wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

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Oxidation of cytochrome c2 and of cytochrome c by reaction centers of Rhodospirillum rubrum and Rhodobacter sphaeroides. The effect of ionic strength and of lysine modification on oxidation rates

Cited by 16 publications

References 22 publications

Electron transfer between primary and secondary donors in Rhodospirillum rubrum: evidence for a dimeric association of reaction centers

Electron transfer between primary and secondary donors in Rhodospirillum rubrum: evidence for a dimeric association of reaction centers

Electrostatic and steric control of electron self-exchange in cytochromes c, c551, and b5

Interaction between Cytochrome c2 and Reaction Centers from Purple Bacteria

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