scholarly journals [Nitrotyrosyl]cytochrome c. Studies of the effect of iron binding, protein denaturants and oxidation-reduction potentials

1976 ◽  
Vol 155 (3) ◽  
pp. 589-597 ◽  
Author(s):  
A J Do Nascimento
Keyword(s):  
Cytochrome C ◽  
Ligand Binding ◽  
Stability Constants ◽  
Isoelectric Point ◽  
Iron Binding ◽  
Protein Solution ◽  
Reduction Potentials ◽  
Oxidation Reduction ◽  
Iron Binding Protein ◽  
The Stability

Static measurements of the reaction of ligand binding were done by conventional spectrophotometry. The ligand-binding reactions with nitrated cytochrome c were performed with imidazole, iminazole, CO and NO. The stoicheiometry was found to be 1:1, and the stability constants for the complexes formed between the nitrated cytochrome c and the ligands are: 2.58 × 10(4) M-1 (imidazole); 1.01 × 10(2) M-1 (iminazole); 3.6 × 10(4) M-1 (CO); 2.74 × 10(4) M-1 (NO). It was found that the electrometric potentials at pH 7.0 and 25degreesC of [aminotyrosyl]cytochrome c are E'o form II = 0.115 V and E'o form I = 0.260 V, where forms I and II are two species of protein co-existing in the protein solution. The isoelectric point for the oxidized form of [nitrotyrosyl]cytochrome c was 10.05, at 4degreesC.

scholarly journals Effects of mutating Asn-52 to isoleucine on the haem-linked properties of cytochrome c

1994 ◽  
Vol 302 (1) ◽  
pp. 95-101 ◽  
Author(s):  
A Schejter ◽  
T I Koshy ◽  
T L Luntz ◽  
R Sanishvili ◽  
I Vig ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Site Directed Mutagenesis ◽  
Wild Type ◽  
General Increase ◽  
Reduction Potentials ◽  
Cytochromes C ◽  
In The Wild ◽  
Order Of Magnitude ◽  
The Stability ◽  
Haem Iron

Asn-52 of rat cytochrome c and baker's yeast iso-1-cytochrome c was changed to isoleucine by site-directed mutagenesis and the mutated proteins expressed in and purified from cultures of transformed yeast. This mutation affected the affinity of the haem iron for the Met-80 sulphur in the ferric state and the reduction potential of the molecule. The yeast protein, in which the sulphur-iron bond is distinctly weaker than in vertebrate cytochromes c, became very similar to the latter: the pKa of the alkaline ionization rose from 8.3 to 9.4 and that of the acidic ionization decreased from 3.4 to 2.8. The rates of binding and dissociation of cyanide became markedly lower, and the affinity was lowered by half an order of magnitude. In the ferrous state the dissociation of cyanide from the variant yeast cytochrome c was three times slower than in the wild-type. The same mutation had analogous but less pronounced effects on rat cytochrome c: it did not alter the alkaline ionization pKa nor its affinity for cyanide, but it lowered its acidic ionization pKa from 2.8 to 2.2. These results indicate that the mutation of Asn-52 to isoleucine increases the stability of the cytochrome c closed-haem crevice as observed earlier for the mutation of Tyr-67 to phenylalanine [Luntz, Schejter, Garber and Margoliash (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 3524-3528], because of either its effects on the hydrogen-bonding of an interior water molecule or a general increase in the hydrophobicity of the protein in the domain occupied by the mutated residues. The reduction potentials were affected in different ways; the Eo of rat cytochrome c rose by 14 mV whereas that of the yeast iso-1 cychrome c was 30 mV lower as a result of the change of Asn-52 to isoleucine.

LIGAND-BINDING REACTIONS AND OXIDATION-REDUCTION EQUILIBRIA OF CYTOCHROME C

1975 ◽  
Vol 244 (1 The Biologica) ◽  
pp. 51-59 ◽  
Author(s):  
Abel Schejter ◽  
Irit Aviram ◽  
Rimona Margalit ◽  
Tzipora Goldkorn
Keyword(s):  
Cytochrome C ◽  
Ligand Binding ◽  
Oxidation Reduction

scholarly journals The oxidation-reduction potentials of cytochrome C

1934 ◽  
Vol 114 (789) ◽  
pp. 423-435 ◽  
Keyword(s):  
Cytochrome C ◽  
Protein Complex ◽  
Living Cell ◽  
Total Iron ◽  
Yeast Cells ◽  
Iron Protein ◽  
Low Concentration ◽  
Reduction Potentials ◽  
Oxidation Reduction

Coolidge (1932) studied the oxidation-reduction potentials of cytochrome C. His chief results may be summarized as follows. (1) The E o of cytochrome either in yeast cells or in artificial preparations is the same, viz., +0·260 volts. (2) In solutions of cytochrome C prepared by extraction of yeast with ammonia and by Keilin's method (1930), hæmatin iron accounts for only one-third of the total iron; the rest of the iron is in tire form of a loose iron-protein complex. (3) The low concentration of cytochrome in the living cell and the positive potentials which its solutions record make it unlikely that cytochrome can function as a respiratory catalyst. The results of Coolidge are open to serious criticism.

Stability of Electrolyzed Oxidizing Water and Its Efficacy against Cell Suspensions of Salmonella Typhimurium and Listeria monocytogenes

2003 ◽  
Vol 66 (8) ◽  
pp. 1379-1384 ◽  
Author(s):  
K. A. FABRIZIO ◽  
C. N. CUTTER
Keyword(s):  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Foodborne Pathogens ◽  
Cell Suspensions ◽  
Free Chlorine ◽  
Chlorine Concentration ◽  
Reduction Potentials ◽  
Oxidation Reduction ◽  
The Stability ◽  
Cutting Boards

Electrolyzed oxidizing (EO) water has proved to be effective against foodborne pathogens attached to cutting boards and poultry surfaces and against spoilage organisms on vegetables; however, its levels of effectiveness against Listeria monocytogenes and Salmonella Typhimurium in cell suspensions have not been compared with those of other treatments. In this study, the oxidation reduction potentials (ORPs), chlorine concentrations, and pHs of acidic and basic EO water were monitored for 3 days at 4 and 25°C after generation. There were no differences between the pHs or ORPs of acidic and basic EO waters stored at 4 or 25°C. However, the free chlorine concentration in acidic EO water stored at 4°C increased after 24 h. In contrast, the free chlorine concentration in acidic EO water stored at 25°C decreased after one day. Cell suspensions of Salmonella Typhimurium and L. monocytogenes were treated with distilled water, chlorinated water (20 ppm), acidified chlorinated water (20 ppm, 4.5 pH), acidic EO water (EOA), basic EO water (EOB), or acidic EO water that was “aged” at 4°C for 24 h (AEOA) for up to 15 min at either 4 or 25°C. The largest reductions observed were those following treatments carried out at 25°C. EOA and AEOA treatments at both temperatures significantly reduced Salmonella Typhimurium populations by >8 log10 CFU/ml. EOA and AEOA treatments effectively reduced L. monocytogenes populations by >8 log10 CFU/ml at 25°C. These results demonstrate the stability of EO water under different conditions and that EO water effectively reduced Salmonella Typhimurium and L. monocytogenes populations in cell suspensions.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

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