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 purpose of this study was to investigate the contribution of mitochondrial and cytoplasmic protein synthesis to the biogenesis of cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase EC 1.9.3.1) and rutamycin-sensitive adenosine triphosphatase (ATP phosphohydrolase EC 3.6.1.3) in cultured oocytes of the toad, Xenopus laevis. X. laevis cytochrome oxidase was purified over 23-fold with respect to specific activity and over 29-fold with respect to specific heme a content from oocyte submitochondrial particles. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate separated the enzyme into six subunits with molecular weights of 44,000, 33,000, 23,000, 17,000, 12,000 and 9,500. the synthesis of the three larger subunits is sensitive to chloramphenicol (an inhibitor of mitochondrial protein synthesis), indicating that these subunits are made on mitochondrial ribosomes; the synthesis of the three smaller subunits is sensitive to cycloheximide (an inhibitor of cytoplasmic protein synthesis) and therefore occurs on cytoplasmic ribosomes. X. laevis rutamycin-sensitive ATPase, purified over 19-fold from oocyte submitochondrial pparticles, consists of 10 subunits with molecular weights of 56,000, 53,000, 41,000, 32,000, 29,000, 24,000, 21,000, 17,500 (2), and 11,500 on sodium dodecyl sulfate-polyacrylamide gels. The 29,000, 21,000, and one of the 17,500-dalton polypeptides are synthesized in the presence of cycloheximide and are, therefore, products of mitochondrial protein synthesis; the synthesis of the remaining seven subunits occurs in the presence of chloramphenicol, indicating that these subunits are made on cytoplasmic ribosomes. The synthesis of protein by mitochondria in cultured oocytes appears to be dependent upon cytoplasmic protein synthesis. In the presence of cycloheximide, the mitoribosomal synthesis of the subunits of cytochrome oxidase and rutamycin-sensitive ATPase is detectable only after a prior inhibition of mitochondrial protein synthesis by chloramphenicol. Oocyte mitochondrial ribosomes synthesize at least nine polypeptides after chloramphenicol treatment, three of which are components of neither cytochrome oxidase nor rutamycin-sensitive ATPase.
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PMID:Synthesis of the mitochondrial inner membrane in cultured Xenopus laevis oocytes. 18 93

1. Of various phospholipids tested, lysolecithin was the most efficient in the solubilization of the components of beef heart submitochondrial particles. Lysolecithin solubilized selectively nicotinamide nucleotide transhydrogenase, succinate dehydrogenase, NADH dehydrogenase and oligomycin-sensitive ATPase. Various cytochromes other than cytochrome c were only slightly solubilized. 2. The effect of various parameters, e.g. ionic strength, pH, time of centrifugation, and concentrations of lysolecithin and protein was investigated. Increasing times of centrifugation led to a partial sedimentation of NADH dehydrogenase, and a complete sedimentation of oligomycin-sensitive ATPase and cytochrome oxidase. 3. Further fractionation of the lysolecithin extract by centrifugation in the presence of low concentrations of cholate gave a complete separation of NADH dehydrogenase and transhydrogenase, indicating that these enzymes are not related functionally. 4. With the lysolecithin fractionation procedure a more than 10-fold purification of transhydrogenase was achieved. Polyacrylamide gel electrophoresis of the partially purified transhydrogenase in the presence of sodium dodecyl sulphate showed major increases in protein-stained bands corresponding to between 70 000 and 54 000 daltons. 5. A possible mechanism for the detergent action of lysolecithin involving a specific exchange of bound phospholipids for lysolecithin is discussed.
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PMID:Selective solubilization of the components of the mitochondrial inner membrane by lysolecithin. 18 27

A new method has been developed for isolating synaptic junctional complexes (SJC) of high structural integrity. The major step in the isolation involves homogenization of a synaptosomal membrane (SM) fraction in a biphasic system consisting of Freon 113 and an aqueous phase containing 0.2% Triton X-100. Well-preserved SJCs, along with membrane vesicles, were recovered in the aqueous phase after low-speed centrifugation of the homogenate. The membranes were subsequently separated from the SJCs by centrifugation on a discontinuous sucrose density gradient. The purity and identity of subcellular fractions were monitored by thin sectioning electron microscopy, using specific and nonspecific staining methods. From the electron microscope studies we conclude that SJCs and their components occupy about 65% of the area covered by structures in this fraction. The assay of enzyme activities indicates that homogenization in Triton-Freon and subsequent steps of the isolation procedure affect the activities of Na, K-ATPase, cytochrome oxidase, and acid phosphatase to different extents, but do not cause total inactivation. Electrophoresis of the SJC-enriched fraction on sodium dodecyl sulfate-polyacrylamide gels has demonstrated that a polypeptide which co-migrates with tubulin is the major component in this fraction, and that a polypeptide co-migrating with actin is also present.
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PMID:Isolation of synaptic junctional complexes of high structural integrity from rat brain. 18 64

Cytochrome c oxidase from the inner membrane of yeast mitochondria consists of seven nonidentical protein subunits, three being synthesized on mitochondrial ribosomes (molecular weights I: 43 K, II: 34 K, and III: 24 K) and four being made on cytoplasmic ribosomes (molecular weights IV: 14 K, V: 12 K, VI: 12 K, and VII: 4.5 K). In the present study all four cytoplasmically synthesized subunits of the enzyme were isolated on a large scale using ion exchange chromatography and gel filtration. Their amino acid composition as well as their amino- and carbosy-terminal amino acid residues have been determined. Sequence determinations of subunits IV and VI are already in an advanced state. The sequence of subunit VI is characterized by a large amino-terminal stretch dominated by charged amino acid residues followed by a cluster of hydrophobic amino acids. The binding site of yeast cytochrome oxidase for cytochrome c was studied by chemical crosslinking experiments. The formation of a disulfide bridge between the two proteins was observed by using cytochrome c from yeast modified with 5-thionitrobenzoate at the cysteinyl residue in position 107. Alternatively, a disulfide between yeast cytochrome c and the oxidase could be formed directly by oxidation with copper phenanthroline. Gel electrophoresis of the crosslinked complexes in sodium dodecyl sulfate revealed a new protein band with an apparent molecular weight of 38 K. This new band appears to be derived from cytochrome c and from subunit III of cytochrome oxidase.
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PMID:Structure of cytochrome c oxidase from baker's yeast - a progress report. Preparation of four subunits for amino acid sequence determination and attempts to localize the cytochrome c binding site. 19 98

A carrier protein mediating alanine transport was purified from the membranes of the thermophilic bacterium PS3, by ion exchange chromatography in the presence of both Triton X-100 and urea. The alanine carrier was recovered in the nonadsorbed fraction from either DEAE- or CM-cellulose columns, suggesting that its isoelectric point was in the neutral pH region. The final preparation contained virtually no electron transfer components, ATPase, or NADH dehydrogenase. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that the final preparation consisted of two major protein components with molecular weights of 36,000 and 9,400. Active transport of alanine after incorporation of the alanine carrier into reconstituted proteoliposomes was driven not only by an artificial membrane potential generated by potassium ion diffusion via valinomycin but also by mitochondrial cytochrome oxidase incorporated into the same liposomes and supplemented with both cytochrome c and ascorbic acid. The membrane-integrated portion (TFo) of the ATPase complex uncoupled alanine transport by conducting protons across the membrane.
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PMID:Isolation of the alanine carrier from the membranes of a thermophilic bacterium and its reconstitution into vesicles capable of transport. 19 18

The specific activity of markers-enzymes in the subcellular fractions of the rabbit visual analyzer cortical end, the synaptosomes and mitochondria of nerve cells, changed under the effect of early long deprivation. For cytochromoxidase and Na+, K+-ATPase it lowers considerably in all subfractions, for monoaminoxidase and Mg2+-ATPase it rises mainly in synaptosomes; the activity of acetyl cholinesterase lowers per 1 g of tissue. In the light two weeks later a tendency is observed to normalization of the studied indexes. The specific activity of cytochrome oxidase (except for free mitochondria) and Na+, K+-ATPase reaches the control, that of monoaminoxidase also partially normalizes, but not competely; Mg2+ATPase in all the subfractions is more inhibited than in the control. This evidences for the effect of light deprivation on the activity of the enzymes associated with different cycles of metabolic processes, first of all, of oxidation and ion transport. These changes are reversible when visual impulsation is recovered. Disturbances in chemism at the subcellular level are specific for different enzymic systems and are not the same in certain subfractions of great hemispheres.
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PMID:[Effect of light deprivation on enzymic activity of synaptosomes and mitochondria of rabbit cortex visual region]. 19 70

Purified lipid-depleted cytochrome oxidase, at purity of 12--14 nmol heme a per mg protein, has been shown to contain seven non-identical subunits in the ratio of unity. Their molucular weights on polyacrylamide gel are, in thousands, 40, 21, 14.8, 13.5, 11.6, 9.5, and 7.6 from gel electrophoresis after dissociation in sodium dodecyl sulfate and beta-mercaptoethanol. The molar ratio is determined by the amino acid composition of each subunit obtained from direct hydrolysis of the stained polyacrylamide gel slices. The amino acid composition of the isolated subunits I and II determined by regular hydrolysis method is found practically the same as that from direct hydrolysis of gel slices. The heme-associated polypeptides are identified with subunits of molecular weights of 40.10(3) and 11.6.10(3). One of the two coppers associated with the polypeptide of molecular weight of 21 000. The second copper may be associated with heme in the subunit of 40.10(3). Evidence of the existence of interpolypeptide disulfide linkages is presented.
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PMID:Identification of subunits of bovine heart cytochrome oxidase. 20 Dec 92

Resonance Raman spectra of cytochrome oxidase solubilized in Tween 20 and sodium cholate, and excited at 413.1 nm have been recorded. Differences in the resonance Raman spectra of the two preparations are minimal indicating that the local environment of the hemes is similar in the two preparations. As in the work of Salmeen, et al. (1973) (Biochem. Biophys. Res. Commun. 52, 1100) the strongest band appears at 1358 cm-1. Some of the other bands differ slightly in their band shapes and frequencies when compared to their spectra; these differences can be accounted for by differences in resonance enhancement of the various bands wnen exciting at 441.6 and 413.1 nm. A study of the region from 1350 to 1380 cm-1 as a function of laser intensity (10--130 mW on sample) indicate that the doublet reported by Salmeen, et al. at 1358 and 1372 cm-1 is a result of photoreduction of the preparations. In samples to which potassium ferricyanide had been added, broad luminescence bands appear at 476 and 641 nm from which it is inferred that catalytic amounts of flavin in the preparations are photoreduced providing reducing equivalents to cytochrome oxidase.
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PMID:Resonance Raman spectra of cytochrome oxidase. Evidence for photoreduction by laser photons in resonance with the Soret band. 20 42

1. Hydrophobic interaction chromatography on Octyl-Sepharose CL-4B is used as a new and simple method for the preparation of large amounts of beef-heart cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). 2. The method involves only one cycle of (NH4)2SO4 fractionation before the material is applied to the column. After washing with 10% cholate and 1.5% Tween 80, elution of the enzyme is accomplished with 1% Triton X-100. 3. The enzyme so prepared contains about 10 nmol heme alpha/mg protein and about 0.2% phospholipid. 4. Characterization of the enzyme has been made with optical and EPR spectroscopy and polyacrylamide gel electrophoresis. The preparation appears by these criteria to be at least as good as other purified enzyme preparations. 5. The turnover rate at infinite cytochrome c concentration in 0.1 M sodium phosphate buffer and 0.5% Tween 80 at pH 6.1 is 80 s-1 per functional unit of the enzyme. A more than three-fold activation could be obtained by the addition of phosphatidylcholine at neutral pH.
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PMID:Purification of beef-heart cytochrome c oxidase by hydrophobic interaction chromatography on octyl-Sepharose CL-4B. 20 31

Seven protein subunits of cytochrome c oxidase from bovine heart were isolated by gel filtration in the presence of sodium dodecyl sulphate (subunits I, II and III) and guanidine hydrochloride (subunits V, VI and VII), and ion-exchange chromatography in 6 M urea (subunit IV) after the enzyme had been dissociated in 6 M guanidine hydrochloride. When analysed by highly cross-linked sodium dodecyl sulphate/polyacrylamide gel electrophoresis in the presence of urea, the apparent molecular weights were = I, 36700; II, 24300; III, 20400; IV, 17300; V, 12300; VI, 8700: and VII, 5100. Monospecific rabbit antisera were obtained against subunits I, IV, V, VI and VII and a mixture of subunits II and III. These subunit-specific antisera with the exception of anti-I serum all cross-reacted with the detergent-solubilized native oxidase. Enzymatic studies on purified oxidase indicated that immunoglobulins against subunits II + III, IV, V, VI and VII respectively caused 25, 65, 20, 30 and 25% inhibition while anti-I immunoglobulin did not inhibit the activity. The subunit-specific antisera were used to examine the arrangements of the subunits in the membrane. Enzymatic studies using bovine heart mitochondria and rat liver mitochondrial digitonin particles showed that anti-(II + III) serum, anti-V serum and anti-VII serum all inhibited the oxidase activity while the other antisera did not. On the other hand, results of using 125I-labelled immunoglobulins showed that anti-IV, anti-V and anti-VII sera were bound to the surface of inverted vesicles (matrix side) while all other antisera were not. These results indicate that cytochrome oxidase subunits II and III are situated on the outer surface, and subunit IV is exclusively on the matrix surface while subunits V and VII are exposed on both surfaces of the mitochondrial membrane. Subunits I and VI are buried within the membrane, not exposed on either side.
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PMID:Immunological studies on cytochrome c oxidase: arrangements of protein subunits in the solubilized and membrane-bound enzyme. 21 67


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