Photosynthetic bacteria Chromatium vinosum

Fry B, Gest H, Hayes JM (1984) Isotope effects associated with the anaerobic oxidation of sulfide by the purple photosynthetic bacterium, Chromatium vinosum. FEMS Microbiol Lett 22 283-287 Fry B, Gest H, Hayes JM (1985) Isotope effects associated with the anaerobic oxidation of sulfite and thiosulfate by the photosynthetic bacterium, Chromatium vinosum. FEMS Microbiol Lett 11 111-Til Fry B, Gest H, Hayes JM (1988a) " S/ S fractionation in sulfur cycles catalyzed by anaerobic bacteria. Appl Environ Microbiol 54 250-256... 

The pH at which the line with a -60 mV/pH slope intersects that with 0 m V/pH slope represents the pK value of reduced Qa. which, as noted, is 9.6. A similar midpoint potential-pH dependence has been reported for Chromatium vinosum, Rs. rubrum and Rp. viridis, with pK values of 8.0, 8.8 and 7.8 respectively. Interestingly, the equilibrium midpoint potentials for the chromatophores of these four different photosynthetic bacteria estimated from the point of intersection ofthe lines of 60 and 0 mV/pH slopes are rather similar, lying within a narrow 50 mV range centered at -175 mV. 

The second kind of reaction center, as represented by that of Chromatium vinosum or Rhodopseudo-monas viridis, has a tightly bound c-type cytochrome [see Fig. 2, right]. This so-called reaction center-associated cytochrome is a tetraheme of molecular mass of 40 kDa and structurally quite different from the other known, c-type cytochromes. One of the hemes in this RC-associated, c-type cytochrome also serves as the immediate electron donor to the photooxidized primary donor of the photosynthetic bacteria (either P870 in C. vinosum or P960 in Rp. viridis). The oxidized cytochrome in the tetraheme is in turn reduced by the soluble cytochrome C2. The RC-associated cytochromes are not easily dissociated from the RC, even at high ionic strength. 

On the other hand, carotenoids in light-harvesting complexes of photosynthetic bacteria assume an all-trans configuration, either twisted (as in Rs. rubrum, Chromatium vinosum, md Rp. palustris) or planar (as in Rb. sphaeroides and Rp. capsulata). Note that chain twisting is not ascribed to the type of carotenoid, but rather to some specific interaction between the carotenoid and the protein environment and apparently affects the efficiency of singlet energy transfer. 

Aerobic bacteria such as Azotobacter vinelandii, Alcaligenes eutrophus, and Nocardia opaca, and facultative anaerobes, such as Escherichia coli and various species of Rhizobium and Bradyrhizobium (the symbionts of leguminous plants), also contain hydrogenase, as do photosynthetic bacteria such as Chromatium vinosum, Rhodobacter capsulatus (formerly Rhodopseudomonas capsulata), and Anabaena variabilis (a filamentous cyanobacterium). The thermophilic hydro-... 

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