Structure of cytochrome c′: a dimeric, high-spin haem protein

Nature ◽  
1980 ◽  
Vol 286 (5770) ◽  
pp. 302-304 ◽  
Author(s):  
Patricia C. Weber ◽  
R. G. Bartsch ◽  
M. A. Cusanovich ◽  
R. C. Hamlin ◽  
A. Howard ◽  
...  
Keyword(s):  
Cytochrome C ◽  
High Spin ◽  
Haem Protein

scholarly journals Redox-linked spin-state changes in the di-haem cytochrome c-551 peroxidase from Pseudomonas aeruginosa

1985 ◽  
Vol 230 (1) ◽  
pp. 227-237 ◽  
Author(s):  
N Foote ◽  
J Peterson ◽  
P M Gadsby ◽  
C Greenwood ◽  
A J Thomson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cytochrome C ◽  
High Spin ◽  
Spin State ◽  
High Potential ◽  
Reduced Form ◽  
Inactive Form ◽  
Temperature Spectra ◽  
State Changes ◽  
Haem Protein

Magnetic-c.d., e.p.r. and optical-absorption spectra are reported for the half-reduced form of Pseudomonas aeruginosa cytochrome c-551 peroxidase, a di-haem protein, and its fluoride derivative. Comparison of this enzyme species with oxidized peroxidase shows the occurrence of spin-state changes at both haem sites. The high-potential haem changes its state from partially high-spin to low-spin upon reduction. This is linked to a structural alteration at the ferric low-potential haem group, causing it to change from low-spin to high-spin. Low-temperature spectra demonstrate photolysis of an endogenous ligand of the high-potential haem. In addition, an inactive form of enzyme is examined in which the structural change at the ferric low-potential haem does not occur on reduction of the high-potential haem.

scholarly journals Physicochemical properties of two atypical cytochromes c, Crithidia cytochrome c-557 and Euglena cytochrome c-558

1975 ◽  
Vol 149 (1) ◽  
pp. 155-167 ◽  
Author(s):  
G W Pettigrew ◽  
I Aviram ◽  
A Schejter
Keyword(s):  
Cytochrome C ◽  
Physicochemical Properties ◽  
High Spin ◽  
Visible Spectrum ◽  
Prosthetic Group ◽  
Ph Values ◽  
Cytochromes C ◽  
Kinetics Of ◽  
Alkaline Isomerization ◽  
Mitochondrial Cytochromes

Cytochrome c-557 from Crithidia oncopelti and cytochrome c-558 from Euglena gracilis are mitochondrial cytochromes c that have an atypical haem-binding site. It was of interest to know whether the loss of one thioether bond affected the physicochemical properties of these cytochromes. The thermodynamic parameters of the redox potential were measured. The reaction with imidazole, the kinetics and thermodynamics of the alkaline isomerization and the effect of heating on the visible spectrum are described for the ferricytochromes. The kinetics of the loss of cyanide, the spectral changes occurring on reduction with dithionite at alkaline pH values and the reactivity with CO are described for the ferrocytochromes. In many respects the cytochromes of the two protozoans are very similar to the cytochromes of horse and yeast. The ferricytochromes do, however, undergo a reversible transition to high-spin species on heating, which may be due to the more flexible attachment of the prosthetic group. Similarly the alkaline isomers of cytochromes c-557 and c-558 give rise to high-spin proteins above pH 11. The alkaline isomerization of cytochrome c-558, involves a pKobs. of 10 and kinetics which do not obey the model of Davis et al. [(1974) J. Biol. Chem.249, 2624-2632] for horse cytochrome c. It is proposed that a model involving two ionizations, followed by a conformation change, may fit the data. Both cytochromes c-557 and c-558 combine slowly with CO at neutral pH values.

scholarly journals Cytochrome c″ isolated from Methylophilus methylotrophus. An example of bis-histidine-co-ordinated Fe3+ haem, with near-perpendicular orientation of the ligands

1990 ◽  
Vol 270 (2) ◽  
pp. 413-417 ◽  
Author(s):  
M J Berry ◽  
S J George ◽  
A J Thomson ◽  
H Santos ◽  
D L Turner
Keyword(s):  
Low Temperature ◽  
Cytochrome C ◽  
High Spin ◽  
Magnetic Circular Dichroism ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Water Soluble ◽  
Reduced Form ◽  
Resonance Spectroscopy ◽  
Methylophilus Methylotrophus ◽  
Perpendicular Orientation

Cytochrome c″ (Methylophilus methylotrophus) is a soluble protein, Mr 15,000, possessing one haem which is high-spin in the reduced state but switches to a low-spin form on oxidation. Low-temperature electron-paramagnetic-resonance spectroscopy of the oxidized state shows a low-spin signal at gz = 3.65 with a folded line-shape typical of a haem of low rhombicity, and the near-infrared magnetic-circular-dichroism (m.c.d.) spectra reveal an unusually intense (delta epsilon = 400 M-1.cm-1 at 5 T, 4.2 K) charge-transfer band at 1560 nm, establishing that the oxidized haem is co-ordinated by two His residues in a near-perpendicular orientation. This conformation is well established for transmembrane b cytochromes, but this appears to be the first example in a water-soluble cytochrome. The low-temperature m.c.d. spectra of the reduced form of the protein confirms that the haem contains a high-spin Fe2+ ligated by one His residue. The redox-linked spin-state change releases a His group. Since this residue is likely to bind a proton at pH values less than 6.5, this cytochrome may provide a useful model of a molecular mechanism of a redox-linked proton uptake and release process.

Paramagnetic properties of the low- and high-spin states of yeast cytochrome c peroxidase

2013 ◽  
Vol 57 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Sophie Vanwetswinkel ◽  
Nico A. J. van Nuland ◽  
Alexander N. Volkov
Keyword(s):  
Cytochrome C ◽  
High Spin ◽  
Cytochrome C Peroxidase ◽  
Spin States ◽  
High Spin States ◽  
Paramagnetic Properties

scholarly journals Magnetization curves of haemoproteins measured by low-temperature magnetic-circular-dichroism spectroscopy

1980 ◽  
Vol 191 (2) ◽  
pp. 411-420 ◽  
Author(s):  
A J Thomson ◽  
M K Johnson
Keyword(s):  
Circular Dichroism ◽  
Cytochrome C ◽  
High Spin ◽  
Ground State ◽  
Magnetic Circular Dichroism ◽  
Striking Difference ◽  
Zero Field ◽  
Magnetization Curves ◽  
Horse Heart Cytochrome ◽  
Circular Dichroïsm

The magnetic-circular-dichroism (m.c.d.) spectra of methymyoglobin cyanide and oxidized horse heart cytochrome c were measured in the region of the Soret band over a range of temperatures from 1.5 to 50 K and in fields from 0 to 5T. A similar study has been made with reduced bovine heart cytochrome c oxidase, which contains one high-spin ferrous haem, namely a3. M.c.d. magnetization curves characteristic of an isolated Kramer's ground state with spin S = 1/2. These curves contrast with the magnetization curve of the high-spin ferrous haem with spin S = 2. The electronic ground state of the latter compound contains zero-field components that are thermally accessible over the temperature range of the experiment. Hence the magnetization curves are a complex nested set. The magnetization curves of the S = 1/2 proteins were analysed and it is shown that it is possible to make estimates of the ground-state g-factors even in the presence of rhombic anisotropy, provided that some knowledge of the polarizations of the electronic transitions is available. The striking difference between the m.c.d. magnetization curves of a simple S = 1/2 paramagnet and magnetically complex ground state should prove extremely useful when m.c.d. spectroscopy is sued to probe the magentic properties of metal centres in proteins, and should have wide application beyond the field of haemoproteins.

scholarly journals An investigation by e.p.r. and optical spectroscopy of cytochrome oxidase during turnover

1982 ◽  
Vol 203 (2) ◽  
pp. 483-492 ◽  
Author(s):  
M T Wilson ◽  
P Jensen ◽  
R Aasa ◽  
B G Malmström ◽  
T Vänngård
Keyword(s):  
Steady State ◽  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Optical Spectroscopy ◽  
High Spin ◽  
Electron Flux ◽  
Turnover Rates ◽  
G 12 ◽  
Radical Signal ◽  
O2 Binding

Cytochrome oxidase (EC 1.9.3.1; ferrocytochrome c:oxygen oxidoreductase) was studied during steady-state by optical and e.p.r. methods. Starting with either the ‘resting’ or the ‘pulsed’ enzyme, oxidase, cytochrome c, ascorbate and O2 were mixed and the reaction monitored optically. Tetramethylphenylenediamine was used as mediator to poise the steady-state to the desired reduction level. After mixing, the reaction was quenched by the used of rapid-freeze techniques. The e.p.r. spectra of samples captured at increasing tetramethylphenylenediamine concentrations (i.e. higher electron flux) show decreasing g = 2 (Cu A) and g = 3 (cytochrome a) signals. No Cu B or g = 6 signals (high-spin cytochrome a3) could be found during the reaction. Also, the signal with peaks at g = 1.69, 1.78 and 5 as well as the g = 12 signal was hardly detectable at higher turnover rates. The only new signal appearing during turnover is a radical signal, which is discussed in terms of a protein radical. Finally, a scheme is presented, proposing a catalytic cycle for cytochrome oxidase with respect to the O2 binding Cu B-cytochrome a3 unit.

Does cytochrome-c oxidase exist in both low- and high-spin pulsed forms?

1989 ◽  
Vol 17 (5) ◽  
pp. 897-898
Author(s):  
NIKOLAUS IOANNIDIS ◽  
JOHN M. WRIGGLESWORTH
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
High Spin
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