Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The monoiodotyrosine 74, formyltryptophan 59, mononitrotyrosine 67, and carboxymethylmethionine 80 derivatives of horse cytochrome c are defective in their ability to accept electrons from the succinate-cytochrome c reductase system, while their reactions with purified cytochrome c oxidase are essentially those of the native protein. The 4-nitrobenzo-2-oxa-1,3-diazole derivative of lysine 13 of horse cytochrome c and the bis-phenylglyoxal derivative of arginine 13 of Candida krusei cytochrome c have the opposite properties, in that they are readily reduced by the succinate-cytochrome c reductase (EC 1.3.99.1) system but are defective in their capability of transferring electrons to cytochrome c oxidase (EC 1.9.3.1). We conclude that electrons from mitochondrial cytochrome c reductase are transmitted to ferricytochrome c by a different pathway than electrons from ferrocytochrome c to cytochrome c oxidase. The present results are compatible with the concept that the mechanism of reduction involves an aromatic ring channel comprising residues 74, 59, 67, and 80, leading from the "left back" part of the protein to the heme iron. On the other hand, since residue 13 is immediately above the edge of the heme that is at the "front surface" of the molecule, we suggest that the electron leaves ferrocytochrome c to cytochrome c oxidase by way of the edge of pyrrole ring II or the adjacent surface-located sulfur of cysteinyl residue 17, which is thioether bonded to the heme. On this basis, the sites of electron entry and exit in cytochrome c would appear to be some 110 degrees of arc away from each other along the surface of the protein, explaining several previously observed phenomena.
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PMID:Separate intramolecular pathways for reduction and oxidation of cytochrome c in electron transport chain reactions. 436 86

The preparation, purification, and characterization of four new derivatives of cytochrome c trifluoroacetylated at lysines 72, 79, 87, and 88 are reported. The redox reaction rates of these derivatives with cytochrome b5, cytochrome c1 and cytochrome oxidase indicated that the interaction domain on cytochrome c for all three proteins involves the lysines immediately surrounding the heme crevice. Modification of lysines 72, 79, 87 had a large effect on the rate of all three reactions, while modification of lysine 88 had a very small effect. Even though lysines 87 and 88 are adjacent to one another, lysine 87 is at the top left of the heme crevice oriented towards the front of cytochrome c, while lysine 88 is oriented more towards the back. Since the interaction sites for cytochrome c1 and cytochrome oxidase are essentially identical, cytochrome c probably undergoes some type of rotational diffusion during electron transport.
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PMID:Use of specific trifluoroacetylation of lysine residues in cytochrome c to study the reaction with cytochrome b5, cytochrome c1, and cytochrome oxidase. 625 May 89

The reactions of horse heart cytochrome c with succinate-cytochrome c reductase and cytochrome oxidase were studied as a function of ionic strength using both spectrophotometric and oxygen electrode assay techniques. The kinetic parameter Vmax/Km for both reactions decreased very rapidly as the ionic strength was increased, indicating that electrostatic interactions were important to the reactions. A new semiempirical relationship for the electrostatic energy of interaction between cytochrome c and its oxidation-reduction partners was developed, in which specific complementary charge-pair interactions between lysine amino groups on cytochrome c and negatively charged carboxylate groups on the other protein are assumed to dominate the interaction. The contribution of individual cytochrome c lysine amino groups to the electrostatic interaction was estimated from the decrease in reaction rate caused by specific modification of the lysine amino groups by reagents that change the charge to 0 or -1. These estimates range from -0.9 kcal/mol for lysines immediately surrounding the heme crevice of cytochrome c to 0 kcal/mol for lysines well removed from the heme crevice region. The semiempirical relationship for the total electrostatic energy of interaction was in quantitative agreement with the experimental ionic strength dependence of the reaction rates when the parameters were based on the specific lysine modification results. The electrostatic energies of interaction between cytochrome c and its reductase and oxidase were nearly the same, providing additional evidence that the two reactions take place at similar sites on cytochrome c.
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PMID:Electrostatic interaction of cytochrome c with cytochrome c1 and cytochrome oxidase. 626 12

The subunits of the cytochrome oxidase from bovine heart were isolated in large quantities suitable for amino acid sequence studies. The preparation of subunits III, IV, V, VI, and VII for sequence determination can be achieved without employing sodium dodecyl sulfate. The method presented essentially involves pyridine extraction, pH fractionation, ammonium sulfate fractionation, and various types of column chromatography. However, subunits I and II can be prepared only in the presence of sodium dodecyl sulfate by molecular sieve chromatography; subunit III can also be isolated in this manner. The separation of subunits is found to be hindered by phospholipids associated with the enzyme and therefore the phospholipid-depleted preparation is used as the starting material. The molecular weights of subunits I, II, III, IV, V, VI, and VII are 40,000, 21,000, 14,800, 13,500, 11,600, 9,500, and 7,600, respectively. These values are based on the results of the conventional Weber and Osborn method of gel electrophoresis in the presence of sodium dodecyl sulfate. The amino termini of subunits I and II have been determined as N-formylmethionine, and those of subunits III, IV, V, VI, and VII are alanine, alanine, serine, alanine, and an N-acetyl-blocked residue, respectively. The carboxyl termini for subunits I to VII are lysine, leucine, lysine, histidine, valine, isoleucine, and valine, respectively. The complete amino acid sequence of some subunits has been published and that of other subunits will be reported elsewhere in collaboration with the Amino Acid Sequence Group of Cytochrome Oxidase at the University of Hawaii.
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PMID:Large scale isolation and properties of subunits from bovine heart cytochrome oxidase. 627 Jan 41

The kinetics of oxidation of horse cytochrome c and the trifluoromethylphenylcarbamylated lysine-13 derivative by cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1) were compared using both spectrophotometric and polarographic methods under different experimental conditions. The rate constants measured spectrophotometrically in 0.025 M tris-cacodylate buffers were similar with the two cytochrome at pH 7.8, but those with the derivative were slightly higher at pH 6. Rates measured with polarographic assays in these buffers were the same with the horse and the derivative cytochromes c at pH 6, but at pH 7.8 the rates with the derivative were less at cytochrome c concentrations between 0.05 and 0.5 micro M and were greater at higher concentrations. The pH optima in the polarographic assays of the derivative and the native pigments were different in 0.025 M Tris-cacodylate buffers; in spectrophotometric assays at pH 7.8 the trifluoromethylphenylcarbamylated lysine-13 cytochrome c showed a greater sensitivity to changes in ionic strength than did the native cytochrome. The variations in apparent Km and V values calculated from spectrophotometric and polarographic assays with the two cytochromes cannot be explained as due to changes in binding of cytochrome c to cytochrome oxidase. The large excess of O2 uptake seen in polarographic assays with horse cytochrome c over that expected from spectrophotometric measurements was not apparent with the trifluoromethylphenylcarbamylated lysine-13 derivative. Thus, the derivative seems to have decreased ability to form the combination of cytochrome c with the oxidase giving high turnover rates.
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PMID:The reaction of the trifluoromethylphenylcarbamylated lysine-13 derivative of horse cytochrome c with cytochrome oxidase. 627 98

The complete primary structure of bovine heart cytochrome c1 was established by analyses of peptide fragments prepared by digestion using trypsin, staphylococcal protease, and chymotrypsin and by cyanogen bromide cleavage of cytochrome c1 and its derivatives. The total number of amino acid residues is 241, giving a molecular weight of 27,924 including the heme group. The NH2- and COOH-terminal residues are serine and lysine, respectively. One characteristic of the protein is that cytochrome c1 contains 43.6% hydrophobic residues and the polarity is estimated to be 41.1%. No clear homology was found between cytochrome c1 and other membranous proteins such as cytochrome b5 or the subunits of cytochrome oxidase for which sequences have been reported. Cytochrome c1 is predicted to have a high content of alpha-helix (46%). Partial sequence studies were also carried out on cytochrome c1 preparations obtained by different procedures and showed that there is no difference among the sequences of various preparations of cytochrome c1. The presence of a hydrophobic cluster near the COOH-terminal region indicates that the COOH-terminal region of cytochrome C1 associates with, or is buried in, the phospholipid bilayer of the mitochondrial membrane.
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PMID:Structural studies of bovine heart cytochrome c1. 628 15

A protein with pore-forming activity has been isolated from the outer membrane of rat liver mitochondria. The purification involves sucrose gradient centrifugation, differential centrifugation in the presence of Triton X-100, and DEAE-Sepharose and CM-Sepharose chromatography. The yield of the purified protein was approx. 2% of the total outer membrane proteins. The protein, when inserted into soya bean phospholipid vesicles, increases the [3H]sucrose permeability of the vesicles but had no effect on the permeability of high-molecular-weight [14C]dextran (Mr 70 000). The protein is very active, since as little as 3-4 micrograms of protein per mg of phospholipid is required for the complete release of [3H]sucrose from the vesicles. Sucrose diffusion channels could not be reconstituted with other membrane proteins such as rat liver cytochrome oxidase or cytochrome b5. Purified pore protein revealed a single band of apparent Mr 30000 when resolved by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. This polypeptide could be further resolved by isoelectric focusing into a major (pI7.9) and two relatively minor (pI7.6 and 7.2) components. Proteolytic mapping with V8 proteinase from Staphylococcus aureus suggests that these probably represent a single component showing charge heterogeneity. The reason for the charge heterogeneity is not known. The amino acid composition of the protein revealed 47.8% polar amino acids with a relatively high lysine content.
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PMID:Purification of a protein having pore forming activity from the rat liver mitochondrial outer membrane. 629 64

Cytochrome oxidase is purified from rat liver and beef heart by affinity chromatography on a matrix of horse cytochrome c-Sepharose 4B. The success of this procedure, which employs a matrix previously found ineffective with beef or yeast oxidase, is attributed to thorough dispersion of the enzyme with nonionic detergent and a low density of cross-linking between the lysine residues of cytochrome c and the cyanogen bromide activated Sepharose. Beef heart oxidase is purified in one step from mitochondrial membranes solubilized with lauryl maltoside, yielding an enzyme of purity comparable to that obtained on a yeast cytochrome c matrix [Azzi, A., Bill, K., & Broger, C. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 2447-2450]. Rat liver oxidase is prepared by hydroxyapatite and horse cytochrome c affinity chromatography in lauryl maltoside, yielding enzyme of high purity (12.5-13.5 nmol of heme a/mg of protein), high activity (TN = 270-400 s-1), and very low lipid content (1 mol of DPG and 1 mol of PI per mol of aa3). The activity of the enzyme is characterized by two kinetic phases, and electron transfer can be stimulated to maximal rates as high as 650 s-1 when supplemented with asolectin vesicles. The rat liver oxidase purified by this method does not contain the polypeptide designated as subunit III. Comparisons of the kinetic behavior of the enzyme in intact membranes, solubilized membranes, and the purified delipidated form reveal complex changes in kinetic parameters accompanying the changes in state and assay conditions, but do not support previous suggestions that subunit III is a critical factor in the binding of cytochrome c at the high-affinity site on oxidase or that cardiolipin is essential for the low-affinity interaction of cytochrome c. The purified rat liver oxidase retains the ability to exhibit respiratory control when reconstituted into phospholipid vesicles, providing definitive evidence that subunit III is not solely responsible for the ability of cytochrome oxidase to produce or respond to a membrane potential or proton gradient.
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PMID:Lipid and subunit III depleted cytochrome c oxidase purified by horse cytochrome c affinity chromatography in lauryl maltoside. 630 17

The reaction of the cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) of Paracoccus denitrificans cytoplasmic membranes with the endogenous cytochrome c of the membranes was studied, as well as its interaction with added exogenous cytochrome c from P. denitrificans or bovine heart. The polarographic method was employed, using N,N,N',N'-tetramethyl-p-phenylenediamine plus ascorbate to reduce the cytochrome c. We found that overall electron transport can proceed maximally while the cytochrome c remains membrane bound; NADH or succinoxidase activities were not inhibited by the addition of substances which bind the P. denitrificans cytochrome c strongly. In contrast to our observations with the spectrophotometric method (Smith, L., Davies, H.C. and Nava, M.E. (1976) Biochemistry 15, 5827-5831), in the polarographic assays the membrane-bound oxidase reacts with about equal rapidity with exogenous bovine and P. denitrificans cytochromes c. The reaction of the oxidase with the endogenous cytochrome c proceeds at high rates and preferentially to that with exogenous cytochrome c; the reaction with the latter, but not the former is inhibited by positively charged poly(L-lysine). The cytochrome c and the oxidase appear to be very closely associated on the membrane.
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PMID:Reaction of cytochrome c in the electron-transport chain of Paracoccus denitrificans. 631 59

Even 70 years ago Gram-negative coccobacilli had been recognized in vaginal discharge and were cultured 30 years ago. The need to have blood in agar medium for cultivation suggested that the organisms might be a Haemophilus species. Later, however, growth characteristics and other features resulted in their being placed in the genus Corynebacterium, before it was realized that this was inappropriate and they were transferred to a new genus and species Gardnerella vaginalis. The organisms are Gram-variable, non-sporing, non-flagellate, non-motile coccobacilli of average size 0.4 X 1-1.5 microns. The cell wall is laminated and some strains possess pili. G. vaginalis is fermentative and dextrose, fructose, galactose, glucose, maltose, mannose, ribose and starch are most likely to be metabolized. However, published patterns of the sugars fermented vary widely and most workers do not rely on such tests as a means of identification. Of many other features exhibited by G. vaginalis, the following are outstanding: it does not produce catalase, cytochrome oxidase, hydrogen sulphide, indole, or urease. Nor does it degrade aesculin, liquefy gelatin, reduce nitrate, or decarboxylate arginine, lysine or ornithine. On the other hand, it is sensitive to hydrogen peroxide, often causes beta-haemolysis and usually hydrolyses hippurate and starch. G. vaginalis is serologically heterogeneous and causes haemagglutination which is mannose resistant. It is resistant to several antibiotics, including amphotericin, colistin, nalidixic acid and gentamicin, which may be incorporated in selective media.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The bacteriology of Gardnerella vaginalis. 639 9


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