scholarly journals Studies on the biosynthesis of cytochrome c

1973 ◽  
Vol 134 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Emer M. Colleran ◽  
O. T. G. Jones
Keyword(s):  
Cytochrome C ◽  
Specific Radioactivity ◽  
Intermediate Formation ◽  
Maximum Deviation ◽  
Midpoint Potential ◽  
Oxidation Reduction ◽  
High Specific Radioactivity ◽  
Absolute Requirement ◽  
Mammalian Mitochondria ◽  
Cytochromes C

A soluble cytochrome was isolated and purified from the slime mould Physarum polycephalum and identified as cytochrome c by room-temperature and low-temperature (77°K) difference spectroscopy. A close similarity between P. polycephalum and mammalian cytochromes c was suggested by a comparison of the initial rates of oxidation of both proteins by mammalian mitochondria. This similarity was further emphasized by redox titrations and gel-electrophoretic studies which indicated that P. polycephalum cytochrome c has an oxidation–reduction midpoint potential of +257mV at pH7.0 and a molecular weight of 12500±1500 (mean±maximum deviation for a set of six measurements). P. polycephalum exhibits an absolute requirement for protohaemin for growth. The 59Fe-labelled haemin was prepared by chemical synthesis from protoporphyrin. The purified product had a specific radioactivity of 0.8±0.02μCi/mol. Growth of P. polycephalum in the presence of [59Fe]haemin resulted in the incorporation of 59Fe into the plasmodial cytochrome c. The specific radioactivity of the cytochrome c haem was 0.36±0.02μCi/mol. The high specific radioactivity of the cytochrome haem indicates that synthesis of the holoenzyme must proceed by direct attachment of haem to the apoprotein rather than by the intermediate formation of a protoporphyrinogen–apoprotein complex. The observed decrease in the specific radioactivity of the haem group is attributed to exchange of the 59Fe with unlabelled iron in the plasmodia either before or during attachment of the haem group to the apoprotein.

Increasing the redox potential of isoform 1 of yeast cytochrome c through the modification of select haem interactions

2002 ◽  
Vol 362 (2) ◽  
pp. 281-287 ◽  
Author(s):  
C. Marc LETT ◽  
J. Guy GUILLEMETTE
Keyword(s):  
Cytochrome C ◽  
Redox Potential ◽  
Point Mutations ◽  
Cd Spectroscopy ◽  
Wild Type ◽  
Mutant Proteins ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Biophysical Studies ◽  
Cytochromes C

The oxidation—reduction potential of eukaryotic cytochromes c varies very little from species to species. We have introduced point mutations into isoform 1 of yeast cytochrome c (iso-1-cytochrome c) to selectively engineer a protein with a higher redox potential. Of the ten different mutant proteins generated for the present investigation Y67R, Y67K and W59H were found to be non-functional. Three other mutant proteins, L32M, L32T and T49K, were functional, but too unstable for biophysical studies. Mutant cytochromes c K79S, K79T, Y48H and Y48K were purified and characterized. The Y48K mutant is the only one that exhibits a significant increase of +117mV in redox potential compared with the wild-type protein while still supporting oxidative phosphorylation invivo. Low temperature difference spectroscopy confirmed the formation of the holoprotein, while adsorption and CD spectroscopy reveal perturbations in the structure of Y48K iso-1-cytochrome c.

scholarly journals Comparison of yeast and beef cytochrome c oxidases. Kinetics and binding of horse, fungal, and Euglena cytochromes c.

1979 ◽  
Vol 254 (23) ◽  
pp. 11973-11981 ◽  
Author(s):  
J.K. Dethmers ◽  
S. Ferguson-Miller ◽  
E. Margoliash
Keyword(s):  
Cytochrome C ◽  
Cytochromes C

scholarly journals Multiple low spin forms of the cytochrome c ferrihemochrome. EPR spectra of various eukaryotic and prokaryotic cytochromes c.

1977 ◽  
Vol 252 (2) ◽  
pp. 574-582 ◽  
Author(s):  
D L Brautigan ◽  
B A Feinberg ◽  
B M Hoffman ◽  
E Margoliash ◽  
J Preisach ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Epr Spectra ◽  
Cytochromes C

scholarly journals The amino acid sequence of cytochromes c-551 from three species of Pseudomonas

1973 ◽  
Vol 131 (3) ◽  
pp. 485-498 ◽  
Author(s):  
R. P. Ambler ◽  
Margaret Wynn
Keyword(s):  
Amino Acids ◽  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Cytochrome C ◽  
Amino Acid Sequence ◽  
Amino Acid Sequences ◽  
Mitochondrial Cytochrome ◽  
Cytochromes C ◽  
Lending Library ◽  
Single Peptide

The amino acid sequences of the cytochromes c-551 from three species of Pseudomonas have been determined. Each resembles the protein from Pseudomonas strain P6009 (now known to be Pseudomonas aeruginosa, not Pseudomonas fluorescens) in containing 82 amino acids in a single peptide chain, with a haem group covalently attached to cysteine residues 12 and 15. In all four sequences 43 residues are identical. Although by bacteriological criteria the organisms are closely related, the differences between pairs of sequences range from 22% to 39%. These values should be compared with the differences in the sequence of mitochondrial cytochrome c between mammals and amphibians (about 18%) or between mammals and insects (about 33%). Detailed evidence for the amino acid sequences of the proteins has been deposited as Supplementary Publication SUP 50015 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1973), 131, 5.

Sulphide as an inhibitor and electron donor for the cytochrome c oxidase system

1982 ◽  
Vol 60 (6) ◽  
pp. 613-623 ◽  
Author(s):  
P. Nicholls ◽  
J.-K. Kim
Keyword(s):  
Cytochrome C ◽  
Oxygen Uptake ◽  
Cytochrome C Oxidase ◽  
Submitochondrial Particles ◽  
Inhibitory Interaction ◽  
Cytochromes C ◽  
Subsequent Step ◽  
Oxidase Enzyme ◽  
Rapid Reaction ◽  
The One

Anomalies both kinetic and equilibrium in nature are described for the inhibition of cytochrome c oxidase activity by sulphide in the isolated enzyme and in submitochondrial particles. These anomalies are related to the involvement of more than 1 mol of sulphide in the blockage of one cytochrome aa3 centre. Sulphide reduces resting cytochrome a3, a reaction that results in oxygen uptake and the loss of a sulphide molecule. Sulphide can also reduce cytochromes c and a; in the former case, a part of the one-equivalent oxidation product, presumed to be the SH∙ radical, reacts with oxygen. Such oxygen uptake is also seen under aerobic conditions when ferricyanide reacts with sulphide. Three phases are identified in the inhibitory interaction of sulphide with the cytochrome c oxidase enzyme itself: an initial rapid reaction involving sulphide oxidation, oxygen uptake, and conversion of cytochrome aa3 into the low-spin "oxyferri" form; a subsequent step in which sulphide reduces cytochrome a; and the final inhibitory step in which a third molecule of sulphide binds the a3 iron centre in the cytochrome [Formula: see text] (oxy) species to give cytochrome [Formula: see text]. The initial events parallel some of the events in the interaction of the cytochrome c – cytochrome aa3 system with monothiols; the final inhibitory event resembles that with cyanide.

scholarly journals Purification and properties of a cross-linked complex between cytochrome c and cytochrome c peroxidase

1982 ◽  
Vol 201 (1) ◽  
pp. 9-18 ◽  
Author(s):  
G W Pettigrew ◽  
S Seilman
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Peroxidase ◽  
Sodium Phosphate Buffer ◽  
Oxidation Reduction ◽  
Purification And Properties ◽  
Lysine Residues ◽  
The Cross ◽  
Nadh Cytochrome ◽  
Stable Association ◽  
Covalently Linked

Cytochrome c (horse heart) was covalently linked to yeast cytochrome c peroxidase by using the cleavable bifunctional reagent dithiobis-succinimidyl propionate in 5 mM-sodium phosphate buffer, pH 7.0. A cross-linked complex of molecular weight 48 000 was purified in approx. 10% yield from the reaction mixture, which contained 1 mol of cytochrome c and 1 mol of cytochrome c peroxidase/mol. Of the total 40 lysine residues, four to six were blocked by the cross-linking agent. Dithiobis-succinimidylpropionate can also cross-link cytochrome c to ovalbumin, but cytochrome c peroxidase is the preferred partner for cytochrome c in a mixture of the three proteins. The cytochrome c cross-linked to the peroxidase can be rapidly reduced by free cytochrome c-557 from Crithidia oncopelti, and the equilibrium obtained can be used to calculate a mid-point oxidation-reduction potential for the cross-linked cytochrome of 243 mV. Mitochondrial NADH-cytochrome c reductase will reduce the bound cytochrome only very slowly, but the rate of reduction by ascorbate at high ionic strength approaches that for free cytochrome c. Bound cytochrome c reduced by ascorbate can be re-oxidized within 10s by the associated peroxidase in the presence of equimolar H2O2. In the standard peroxidase assay the cross-linked complex shows 40% of the activity of the free peroxidase. Thus the intrinsic ability of each partner in the complex to take part in electron transfer is retained, but the stable association of the two proteins affects access of reductants.

Sign in / Sign up

Export Citation Format

Share Document