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R G Bartsch

Publications and source records attributed to R G Bartsch.

At least 55 records · Page 3Linked to original sources
PubMed1979

The amino acid sequence of cytochrome c' from the purple sulphur bacterium Chromatium vinosum.

An amino acid sequence is proposed for the cytochrome c' from the photosynthetic purple sulphur bacterium Chromatium vinosum strain D. It is single polypeptide chain of 131 residues, with haem-attachment cysteine residues at positions 121 and 124. The results discredit an earlier report [Dus, Bartsch & Kamen (1962) J. Biol. Chem 237, 3083--3093] of a di-haem peptide sequence from this protein. The sequence belongs to the same class as the published Alcaligenes and Rhodospirillum rubrum cytochrome c' squences, but the resemblance is not close. Detailed evidence for the amino acid sequence of the protein has been deposited as Supplementary Publication SUP 50,093 (15 pp.) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies may be obtained on the terms given in Biochem. J. (1978) 169, 5.

Amino Acid Sequence↗
PubMed1979

Extracellular hydrogenase from photosynthetic bacterium, Rhodospirillum rubrum.

With Rhodospirillum rubrum, hydrogenase was found to exist partly as an extracellular enzyme in the culture medium. After 4-day cultivation, the total activity and the specific activity of the enzyme in the medium were about 10 times and 230 times as high as those in the crude extract obtained from disrupted cells. The time course for the production of hydrogenase during cultivation was studied.

Hydrogen↗
PubMed1978

Redox potentials of the photosynthetic bacterial cytochromes c2 and the structural bases for variability.

The cytochromes c2 of the Rhodospirillaceae show a much greater variation in redox potential and its pH dependence than the mitochondrial cytochromes c that have been studied. It is proposed that the range of redox potential for cytochromes c2 functioning as the immediate electron donor to photo-oxidised bacteriochlorophyll may be 345-395 mV at pH 5. Closely related cytochromes c2 with different redox potentials show patterns of amino acid substitution which are consistent with changes in hydrophobicity near the haem being at least a partial determinant of redox potential. More distantly related cytochromes are difficult to compare because of the large number of amino acid substitutions and the probability that there are subtle changes in overall peptide chain folding. The redox potential versus pH curves can be analysed in terms of either one ionisation in the oxidised form or two in the oxidised form and one in the reduced. The pK in the oxidised form at higher pH values can be correlated with the pK for the disappearance or shift of the near infrared absorption band located near 695 nm. The structural bases of these ionisations are not known but the possible involvement of the haem propionate residues is discussed.

Amino Acids↗
PubMed1978

Complete stabilization of water-soluble hydrogenase from Rhodospirillum rubrum under air atmosphere with a high concentration of chloride ions.

Hydrogenase was easily solubilized from light-grown cells of R. rubrum with 10 mM Na ethylenediaminetetraacetate. The enzyme thus obtained was so stable that loss of its activity was undetectable during storage at room temperature for 6 months under air atmosphere, provided that NaCl, KCl or CsCl was present at greater than or equal to 0.7 M.

Aerobiosis↗
PubMed1976

pH dependence of the oxidation-reduction potential of cytochrome c2.

The pH dependence of the spectra and of the oxidation-reduction potential of three cytochromes c2, from Rhodopseudomonas capsulata, Rhodopseudomonas sphaeroides and Rhodomicrobium vannielii, were studied. A single alkaline pK was observed for the spectral changes in all three ferricytochromes. In Rps. capsulata cytochrome c2 this spectroscopic pK corresponds to the pK observed in the dependence of oxidation-reduction potential on pH. For the other two cytochromes the oxidation-reduction potential showed a complex dependency on pH which can be fitted to theoretical curves involving three ionizations. The third ionization corresponds to the ionization observed in the spectroscopic studies but the first two occur without changes in the visible spectra. The possible structural bases for these ionizations are discussed.

Cytochrome c Group↗
PubMed1975

Amino acid sequence of cytochrome c' from the purple photosynthetic bacterium Rhodospirillum rubrum S1.

The amino acid sequence of cytochrome c' from the purple photosynthetic bacterium Rhodospirillum rubrum S1 has been determined and is consistent with homology to cytochrome c' from the nonphotosynthetic bacterium Alcaligenes sp. NCIB 11015. There is 29% identity in the chosen alignment of these two proteins. R. rubrum cytochrome c' is composed of a single peptide chain of 126 amino acid residues with a single heme covalently bound near the COOH terminus. There is no sequence similarity to mitochondrial cytochrome c, except at the heme binding site.

Amino Acid Sequence↗
PubMed1973

Spin-state correlations in near infrared spectroscopy of cytochrome c'.

Characteristic absorption spectra in the ultraviolet, visible, and near infrared regions are correlated with spin state in ferriheme proteins. Weak, diffuse bands in the near infrared exhibit maxima at about 1000-1100 nm (high spin) and at about 1450-1750 nm (low spin). In these and earlier studies such correlations have been established for several ferriheme proteins, but less extensively than in the more well-known cases of Soret and visible band maxima. We have strengthened the correlation in the near infrared by measurements of absorption spectra in Rhodospirillum rubrum cytochrome c', a variant c-type cytochrome that exhibits a pH-induced transition from high-spin to low-spin state as the pH varies from 6.3 to 13.1. Data are provided on extinction coefficients of characteristic absorption bands at various pH values, obtained by comparison with those measured under the same conditions for horse-heart ferricytochrome c. It is concluded that good correlations of spin state with absorption behavior exist over the entire spectroscopic range from 250 to 2500 nm and that the basic assignments of absorption bands to in-plane charge transfer processes are consistent with these correlations.

Cytochrome c Group↗
PubMed1972

Observations on light-induced oxidation reactions in the electron transport system of Chromatium.

Light-induced cytochrome oxidations in Chromatium subchromatophore particles were studied in detail. These reactions were found to be dependent not only on redox potential, but also on the efficiency of coupling of the redox buffer electrons to the cytochrome system. Light-induced oxidation of the high potential cytochrome (c-556) was dependent on (a) the availability of reduced cytochrome and (b) the rate of light-induced oxidation (as determined by light intensity) vs. rate of cytochrome rereduction. Chromatium high potential iron-sulfur protein ("HiPISP") enhanced the rate of c-556 rereduction by mediating electron flow from artificial redox buffers to c-556. In these experiments, the light-induced oxidation of the low potential cytochrome (c-552.5) is dependent not only on the above parameters, but also on the rate of oxidation of the primary electron acceptor X. The interactions of purified Chromatium cytochromes with the light-induced cytochrome oxidation system are discussed.

Bacterial Proteins↗
PubMed1972

On the monohene character of cytochromes c'.

Interpretations of data bearing on structures of cytochromes cc'-a class of variant c-type heme proteins from bacteria-in support of a diheme-bearing single chain as a basic structural unit, appear to be invalid in the light of recent studies. These reveal that nearly all members of this class exist as dimers that can be dissociated into, if they do not already exist as, monoheme-bearing monomers. The particular case of the Chromatium protein, held to be the source of a peptic-"core" peptide containing two covalently-bonded heme groups, has been re-examined by preparation of tryptic and chymotryptic peptides derived from the heme-bearing region of the protein, as well as by repetition of experiments on peptic digestion, with more rigorous purification of the resultant peptides than was previously done. It is shown that this protein can also be dissociated into identical subunits, bearing a single heme prosthetic group, and accounting essentially for all its heme content. Thus, the previous terminology-cytochromes cc'-based on supposition of heme group heterogeneity, is inconsistent with these findings and should be replaced by cytochromes c'.

Amino Acid Sequence↗