Cytochrome Rhodospirillum rubrum

Fig. 7. The absorption spectra of oxidised rhodospirillum rubrum cytochrome cc (oxidised) with change of pli...

Fig. 8. The absorption spectra of reduced rhodospirillum rubrum cytochrome cc with change of pH. This figure and figure 7 are reproduced with permission (67)...

Ferricytochrome c 2 (Rhodospirillum rubrum) Cytochrome c 550 Paracoccus denitrijicans) Ribonuclease A (bovine)... 

Cytochrome from Rhodospirillum rubrum. ( 2itJ 5S 0.967). Purified by chromatography on a column of CM-Whatman cellulose [Paleus and Tuppy Acta Chem Scand 13 641 7959]. 

Britt, R. D., Sauer, K., Klein, M. P., Knaff, D. B., Kriauciunas, A., Yu, C. A., Yu, L., and Malkin, R., 1991, Electron spin echo envelope modulation spectroscopy supports the suggested coordination of two histidine ligands to the Rieske Fe-S centers of the cytochrome b6f complex of spinach and the cytochrome bcl complexes of Rhodospirillum rubrum, Rhodobacter sphaeroides, and bovine heart mitochondria. Biochemistry 30 1892nl901. 

The membrane-bound ATP synthetase couples phosphorylation to a proton gradient [90] which is generated by the cyclic electron transfer system (Fig. 3). This system includes the RC, a UQ pool [91], a Cyt bic complex [92,93], and a specialized Cyt c (E j = -fO.34 V) for transferring electrons to the oxidized primary donor (P-870 or P-970 ) of the RC. In some bacteria such as Chromatiurn vi-nosum and Rhodopseudomonas viridis this specialized Cyt c is bound to the RC in the membrane [93,94], whereas in other bacteria such as Rb. sphaeroides and Rhodospirillum rubrum this cytochrome is a periplasmic protein (Cyt C2) that binds to the membrane-bound RC [90]. 

The shorter chains of the 82- to 86-residue cytochromes C550 (from Pseudomonas ), 6553, " and C555 (from Chlorohiumd ) as well as the longer 112-residue polypeptide of cytochrome C2 from Rhodospirillum rubrum have nearly the same folding pattern as that in mitochondrial cytochrome c. However, the 128-residue chain of the dimeric cytochrome c from Rhodospirillum molischianum forms an antiparallel four-helix bundle (Fig. 16-8). This is the same folding pattern present in the ferritin monomer (Fig. 16-3), hemerythrin (Fig. 2-22), and many other proteins including cytochrome 562 of E. coli ° Cytochrome/, which functions in photosynthetic electron transport, is also a c-type cytochrome but with a unique protein fold. ... 

CD measurements in the range 205—500 nm were reported for cytochromes from Rhodospirillum rubrum and Rhodopseudomonas palustris under various conditions, and the relatively high helix content of about 63% was estimated by standard methods for both ferricytochromes (215) [see, however, Ref. (216)]. ORD measurements on Chromatium cytochrome c552, which contains two mesohemes and one flavin per molecule, showed complex behavior in the Soret region, indicating possible interaction between the hemes (217). 

A comparison of CD spectra (200—600 nm) between bovine heart fenicytochrome c and ferricytochrome from Rhodospirillum rubrum showed marked differences, while the spectra were more similar in the reduced forms. These differences were attributed to subtle variations around the hemes rather than to differences in the polypeptide chain conformations (216). Optical activity studies of cytochromes C3 showed similarities among three species of Desulfovibrio but revealed differences from mammalian cytochrome c. Rotatory strengths of the resolved CD... 

The three-dimensional folding of bacterial cytochromes ca and caso as described in refs. S0 31 and 36-38 is shown in Figs. 9 and 10, and the comparison of amino acid sequences with that of tuna c appears in Table VII, The sequence of csso was unknown prior to the X-ray analysis, but an alignment of c and ca sequences substantially identical to that of Table VII had been proposed by Dus et al. 33) when they reported the sequence of Cj from Rhodospirillum rubrum. Recently, the cz sequences from three rhodopseudomonads have been completed by Ambler and co-workers, and these have been included in Table VII for comparison. 

Mbssbauer, and resonance Raman spectra, and the NMR spectra of Chromatium vinosum cytochrome c, but not those of Rhodospirillum rubrum, Rhodospirillum molischianum, and Rhodopseudomonas / a/u57r/5. ... 

Many cytochromes in energy-transducing organelles are membrane-bound proteins. Present in mitochondria and in purple photosynthetic bacteria, the cyt bc complex (also called ubiquinol-cytochrome c oxidoreductase, or complex III) catalyzes the electron transfer from ubiquinol to ferricyt c and pumps protons from the matrix to the cytosol.The catalytic core of the cyt bci complex comprises three redox-active subunits they are a cyt b with two ft-type hemes bn and bf), a cyt Cl, and a Reiske iron sulfur protein. While this catalytic core has enzymatic activity in some a proteobacteria like Paracoccus, Rhodospirillum rubrum, and Rb. capsulatus, mitochondrial cyt bci complexes have an additional seven or eight subunits." ... 

Studies of the sequence changes in cytodirome c found in 30 species ranging from man through moth to castor bean show that the hydrophobic nature of the haem box is conserved. A number of residues on the left side including the aromatics Tyr-59,1 -67, and Tyr-74 are conserved, which is consistent with the importance of this part of the molecule to electron transfer. The character of the basic region is also conserved, which explains the observation that cytochrome c from one species will react in vitro with cytochrome-oxidase preparations from distantly related species. Modelbuilding studies on bacterial cytochromes show that the sequence of cytochrome C from Rhodospirillum rubrum with 114 amino-acids can be easily... 

The paper by Hunyh et al. (1978) on the Mossbauer effect of low-spin Fe " in cytochrome c from Rhodospirillum rubrum highlights the value of analyses that search out fundamental properties of the system. While measurements of the sign of the product QxQyQz can be made using ESR with circularly polarized radiation (see Section 2.2.3), the measurements and analysis by Hunyh et al (1978) provides a valuable alternative. They noted that in Mossbauer spectroscopy under weak magnetic field conditions. 

Cytochrome c from Rhodospirillum rubrum consists of a dimer (mol. wt. 27,500) with identical subunits, each containing a heme prosthetic group (Meyer et a/., 1975). At neutral pH the ESR spectra of the oxidized protein consists of signals with g values close to 5, atypical of either low-spin or high-spin ferric hemes. This observation has been rationalized in terms of... 

We have isolated reaction centers from Rhodospirillum rubrum G- 9 cells labeled with the isotope 39-Fe. On LDS-polyacrylamide electrophoresis the preparation shows the typical three bands H, M and L and some minor contaminations (Figure 1). The specific staining technique for c-type cytochromes gave no positive reaction, indicating that there is no such cytochrome among the contaminations (datanot shown). 

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