Rhodobacter spheroides

Cobb N, T Conrads, R Hille (2005) Mechanistic studies of Rhodobacter spheroides McjSO reductase. J Biol Chem 280 11007-11017. 

Cyclic photophosphorylation in purple bacteria. QH2 is eventually dehydrogenated in the cytochrome bc1 complex, and the electrons can be returned to the reaction center by the small soluble cytochrome c2, where it reduces the bound tetraheme cytochrome or reacts directly with the special pair in Rhodobacter spheroides. The overall reaction provides for a cyclic photophosphorylation (Fig. 23-32) that pumps 3-4 H+ across the membrane into the periplasmic space utilizing the energy of the two photoexcited electrons. 

Chlorophyll. The pathway of chlorophyll synthesis has been elucidated through biochemical genetic studies of Rhodobacter spheroides y]7 118a which produces bacteriochlorophyll, from studies of cyanobacteria,419 420 and from investigations of green algae and higher plants,421 which make chlorophyll a. The first step in the conversion of protoporphyrin IX into chlorophyll is the insertion of Mg2+ (Fig. 24-23, step a). 

A FIGURE 8-35 Three-dimensional structure of the photosynthetic reaction center from the purple bacterium Rhodobacter spheroides. (Top) The L subunit (yellow) and... 

The transfer of an electron from the tetraheme cytochrome c of R. viridis or from the small cytochrome C2 of Rhodobacter spheroides to ChU of the special pair has similar characteristics but is slower than the initial electron transfer from P. On the other hand, electron transfers from to Qg involve two distinct steps and coupled uptake of two protons. An unexplained fact is that photochemical electron transport through the reaction centers always occurs through the L-side to rather than the M-side. However, rapid electron transfer to the pheophytin on the B-side (M-side) has been observed following excifafion with blue light. This may... 

The first step of the heme biosynthetic pathway in mammalian cells involves the condensation of glycine with succinyl-coenzyme A (CoA) to yield 5-aminolevulinate (ALA), carbon dioxide and CoA (Figure 2-1). This reaction is catalyzed by ALA synthase (ALAS E.C. 2.3.1.37) and is considered to be the rate-limiting step in the production of heme in, at least, non-erythroid cells [1, 7, 8]. ALAS was initially discovered in the bacterimn Rhodobacter spheroides and in cMcken erythrocytes in the laboratories of Shemin [9] and Neuberger [10], respectively. However, it was not imtil the 1970s that the enzyme started to be isolated and purified from mammalian sources [11-13]. 

We have recently reported fluorescence from several carotenoids, including 3 Carotene, spheroidenone, spirilloxanthin and rhodopin(2). In this work we present new results on lycopene and spheroidene. Spheroidene has been chosen because it is the carotenoid in the B800-850 antenna complex of Rhodobacter spheroides, while lycopene due to its linear symmetric structure should be a good model for linear polyene. 

Hassan, M. A., Shirai, N., Kusubayashi, N., Abdul Karim, M. L, Nakanishi, K., Hashimoto, K. The production of polyhydroxyalkanoates from anaerobically treated palm oil mill effluent by Rhodobacter spheroides. J Ferment Bioengg 1997a, 83,485-488. 

RC) of Rhodobacter spheroides R26. An exchange at both sites is possible... 

In reaction centers (RC) of Rhodobacter spheroides (Rb.), the tetra-pyrrole pigments at the sites B ("monomeric" bacteriochlorophylls,... 

Fig. 3. Circular dichroism spectra of reaction centers with modified pheophytins, in tris-HCl buffer (20 mM, pH 8) containing LDAO (0.1%). Native RC from Rhodobacter spheroides R26 (bottom), RC after exchange of BPhe a against Phe a (center), and RC after single exchange of BPhe a against [3-acetyl]-Phe a (top). Spectra were normalized to the same absorption at the dimer band (=865 nm).

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