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 complete amino acid sequence of the heme alpha-containing subunit V of bovine heart cytochrome oxidase was determined to be: H2N-Ser-His-Gly-Ser-His-Glu-Thr-Asp-Glu-Glu-Phe-Asp-Ala-Arg-Trp-Val-Thr-Tyr-Phe-Asn-Lys-Pro-Asp-Ile-Asp-Ala-Trp-Glu-Leu-Arg-Lys-Gly-Met-Asn-Thr-Leu-Val-Gly-Tyr-Asp-Leu-Val-Pro-Glu-Pro-Lys-Ile-Ile-Asp-Ala-Ala-Leu-Arg-Ala-Cys-Arg-Arg-Leu-Asn-Asp-Phe-Ala-Ser-Ala-Val-Arg-Ile-Leu-Glu-Val-Val-Lys-Asp-Lys-Ala-Gly-Pro-His-Lys-Glu-Ile-Tyr-Pro-Tyr-Val-Ile-Gln-Glu-Leu-Arg-Pro-Thr-Leu-Asn-Glu-Leu-Gly-Ile-Ser-Thr-Pro-Glu-Glu-Leu-Gly-Leu-Asp-Lys-Val-COOH. The subunit V is a single polypeptide which consists of 109 amino acid residues. The protein contains 48.6% hydrophobic residues and 34.0% hydrophilic residues and it is an acidic protein having a net charge of -3 at neutral pH. The molecular weight of subunit V was calculated to be 12,436 and that for the heme alpha-containing polypeptide was 13,295.
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PMID:Amino acid sequence of subunit V of bovine heart cytochrome oxidase, the heme alpha-containing subunit. 22 Feb 24

Comparison of the human mitochrondial DNA sequence of the cytochrome oxidase subunit II gene and the sequence of the corresponding beef heart protein shows that UGA is used as a tryptophan codon and not as a termination codon and suggests that AUA may be a methionine and not an isoleucine codon. The cytochrome oxidase II gene is contiguous at its 5' end with a tRNAAsp gene and there are only 25 bases at its 3' end before a tRNALys gene. These tRNA'S are different from all other known tRNA sequences.
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PMID:A different genetic code in human mitochondria. 22 94

Between pH approximately 4 and 10 cobaltocytochrome c (Cocyt-c) gives an electron paramagnetic resonance (EPR) spectrum with g parallel = 2.035, g the perpendicular = 2.223, CoA PARALLEL = 61.4 G, CoA the perpendicular = 49.8 G, NA parallel = 15.3 G, and NA THE PERPENDICULAR = 12.5 G. Comparisons with the EPR spectra of deoxycobaltomyoglobin, deoxycobaltohemoglobin, and model compounds and together with other evidence showed cobaltocytochrome c to have Met-80 and His-18 as its axial ligands. The protons of these ligands are seen as resonances shifted by the ring-current field of the porphyrin in the 300-MHZ 1H nuclear magnetic resonance (NMR) spectra of cobalticytochrome c (Cocyt-c+). The methyl and gamma-methylene protons of Met-80 in this molecule occupy positions with respect to heme c which are somewhat different from those in ferrocytochrome c. The 1H NMR spectra also showed that the methyl groups of Leu-32, Ile-75, Thr-63, thioether bridges, and the porphyrin ring in the cobalt protein are in the same state as in native enzyme; the same is also true for Tyr-59, His-26, and His-33 and also possibly Tyr-67, Tyr-74, and Phe-82. Above pH 11, Cocyt-c is converted to a five-coordinated form having g parallel = 2.026, g the perpendicular = 2.325, CoA parallel = 80 G, CoA the perpendicular approximately 10 G, NA parallel = 17.5 G, and NA the perpendicular not resolved. Below pH 1.0 the EPR spectrum of Cocyt-c is also five-coordinated with g parallel = 2.014, g the perpendicular = 2.359, CoA parallel = 93.8 G, and CoA the perpendicular = 38.8 G. The axial ligands in the alkaline and the acidic forms of Cocyt-c are His-18 and Met-80, respectively. New prominent proton resonance peaks are observed in cobalt-cytochrome c which are either absent or weak in native cytochrome c. These are situated at 3.0, 1.7, and 1.44 ppm, attributable, respectively, to the epsilon-CH2, DELTA-CH2 + beta-CH2, and gamma-CH2 of lysyl residues in random-coil-peptides. From the areas of these peaks, it is estimated that one-two lysyl residues in Cocyt-c have been modified; four-five lysyl residues in Cocyt-c+ have been modified. These alterations of surface charged groups are probably responsible for the lowered reactivity of Cocyt-c with cytochrome oxidase and the lack of reactivity of Cocyt-c+ with several cytochrome reductase systems.
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PMID:Cobalt-cytochrome c. II. Magnetic resonance spectra and conformational transitions. 24 Mar 81

The maternally inherited [exn-5] mutant of Neurospora crassa is characterized by its slow-growth rate and deficiency of cytochrome aa3 relative to wild-type strains. We have determined the DNA sequence of the COXI and COXII genes of the mutant, which encode subunits 1 and 2 of cytochrome c oxidase, respectively. No changes in the DNA sequence of the COXI gene relative to the corresponding wild-type gene were found. In the region of the COXII gene we found two alterations, one a C to T transition eight base pairs upstream of the coding sequence and the second within the coding sequence for subunit 2 affecting amino acid 27 of the precursor polypeptide (amino acid 15 of the mature polypeptide). The altered codon in [exn-5] specifies an isoleucine residue rather than the wild-type threonine residue. The corresponding position in subunit 2 sequences of all other organisms examined is conserved either as a threonine or a serine residue. Thus, we consider it likely that the mutation directly affecting the coding sequence of the polypeptide is responsible for the [exn-5] phenotype. Analysis of serially passaged heterokaryons constructed between wild-type and [exn-5] shows that both mutations segregate with the [exn-5] phenotype. Examination of mitochondrial translation products in [exn-5] revealed a deficiency of subunit 2, as well as the presence of a polypeptide that corresponds to a previously described precursor of subunit 1 that accumulates in a COXI mutant of N. crassa, [mi-3]. We propose possible relationships between [exn-5], [mi-3], and the nuclear su-1[mi-3] allele, which suppresses both mutations.
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PMID:Alteration of the cytochrome c oxidase subunit 2 gene in the [exn-5] mutant of Neurospora crassa. 165 11

Human intestinal apolipoprotein (apo) B mRNA undergoes a C to U RNA editing at nucleotide 6666 to generate a translation stop at codon 2153, which defines the carboxy-terminal of apo B48. Here we show that two of eleven human intestinal cDNAs spanning residue 6666 were edited from a genomically-encoded C to a T at residue 6802 as well as at residue 6666. This additional editing converts Thr (ACA) codon 2198 to Ile (AUA). Synthetic RNA including the nucleotide 6802 was edited in vitro by intestinal extracts at 10-15% of the editing efficiency of nucleotide 6666. A sequence is identified as important for recognition by the editing activity. No secondary structural homology was identified between the two edited sites. No other sequence in the region between 6411 and 6893 nucleotides of apo B mRNA was found to be edited in vivo or in vitro. Apo B RNA editing extracts from intestine did not edit maize cytochrome oxidase II mRNA.
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PMID:An additional editing site is present in apolipoprotein B mRNA. 185 58

We have cloned and sequenced over 9 kb of the mitochondrial genome from the sea star Pisaster ochraceus. Within a continuous 8.0-kb fragment are located the genes for NADH dehydrogenase subunits 1, 2, 3, and 4L (ND1, ND2, ND3, and ND4L), cytochrome oxidase subunits I, II, and III (COI, COII, and COIII), and adenosine triphosphatase subunits 6 and 8 (ATPase 6 and ATPase 8). This large fragment also contains a cluster of 13 tRNA genes between ND1 and COI as well as the genes for isoleucine tRNA between ND1 and ND2, arginine tRNA between COI and ND4L, lysine tRNA between COII and ATPase 8, and the serine (UCN) tRNA between COIII and ND3. The genes for the other five tRNAs lie outside this fragment. The gene for phenylalanine tRNA is located between cytochrome b and the 12S ribosomal genes. The genes for tRNA(glu) and tRNA(thr) are 3' to 12S ribosomal gene. The tRNAs for histidine and serine (AGN) are adjacent to each other and lie between ND4 and ND5. These data confirm the novel gene order in mitochondrial DNA (mtDNA) of sea stars and delineate additional distinctions between the sea star and other mtDNA molecules.
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PMID:Nucleotide sequence of nine protein-coding genes and 22 tRNAs in the mitochondrial DNA of the sea star Pisaster ochraceus. 197 16

Mutation of conserved Phe-82 of yeast iso-1 cytochrome c to Tyr, Gly, Ser, Leu, or Ile affects binding to and reaction with cytochrome-c oxidase from beef heart. The observed changes of binding and kinetic constants reflect mutation-induced rearrangements in the heme vicinity brought about by the replacement of Phe-82. Such conformational rearrangements are also revealed by altered circular dichroism spectra of the oxidase-bound mutant cytochromes c. Variations in Km for cytochrome c oxidation do not parallel variations in Kd, the dissociation constant for binding of cytochrome c to the oxidase. This observation does not support an enzymatic mechanism in which the rate of cytochrome c oxidation is governed by product dissociation.
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PMID:Binding and oxidation of mutant cytochromes c by cytochrome-c oxidase. 253 28

A pool of oligonucleotides encoding a start methionine and nine random amino acids was inserted at the 5'-end of the gene for the yeast cytochrome oxidase subunit IV lacking its own mitochondrial targeting sequence. Approximately one-quarter of the randomly generated sequences targeted subunit IV to its correct intramitochondrial location in vivo. Sequence analysis of 89 randomly generated sequences showed that their efficiencies as mitochondrial targeting signals correlated with the potential to fold into an amphiphilic alpha-helix. Functional targeting sequences were enriched in arginine and isoleucine residues but contained few aspartate, glutamate, and proline residues. Nonfunctional sequences predicted to have significant helical amphiphilicity often had at least one acidic or multiple helix-breaking residues that would be expected to interfere with targeting functioning. These results support the hypothesis that the signal for targeting a protein into the mitochondrial matrix is usually a positively charged amphiphilic helix.
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PMID:The mitochondrial targeting function of randomly generated peptide sequences correlates with predicted helical amphiphilicity. 255 47

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

Subunit II of cytochrome-c oxidase contains a redox centre, CuA, with unusual spectroscopic properties; this site consists of two copper atoms and acts as the entry point for electrons from cytochrome c. We have constructed a site-directed mutant of cytochrome-c oxidase from Paracoccus denitrificans in which the CuA site has been disturbed by replacement of Met227 with isoleucine. The purified, fully assembled enzyme complex has been investigated with various techniques including metal analysis, EPR and visible spectroscopies, steady-state and fast kinetics. The stoichiometry of the metals in the enzyme remains unchanged but a clear perturbation of the CuA site can be observed in the EPR and near-infrared optical spectra. It is concluded that in the mutant CuA is still binuclear but that the two nuclei are no longer equivalent, converting the delocalized [Cu(1.5)....Cu(1.5)] centre of the wild type into a localized [Cu(I)....Cu(II)] system. Changes in the overall kinetics of the mutant are correlated with a diminished electron transfer rate between CuA and heme alpha.
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PMID:Perturbation of the CuA site in cytochrome-c oxidase of Paracoccus denitrificans by replacement of Met227 with isoleucine. 853 20


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