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B Kadenbach

Publications and source records attributed to B Kadenbach.

At least 91 records · Page 5Linked to original sources
PubMed1990

Tissue- and species-specific expression of cytochrome c oxidase isozymes in vertebrates.

Cytochrome c oxidase was isolated from brown fat tissue of the rat and compared with the isozymes from rat liver and heart, which differ at least in subunits VIa and VIII. ELISA titrations of COX from the three tissues with monospecific antisera to all 13 subunits of the rat liver enzyme showed differences between the three enzymes. The N-terminal amino-acid sequence analysis of subunits VIa and VIII from SDS-PAGE gel bands of the three enzymes indicates the occurrence of three different isozymes in the rat. N-terminal amino-acid sequence analysis of subunits VIa and VIII from cytochrome c oxidase of bovine and human heart demonstrates also species-specific differences in the expression of the 'liver-type' and 'heart-type' of subunits VIa and VIII.

Adipose Tissue, Brown↗
PubMed1990

The K(+)-ionophores nonactin and valinomycin interact differently with the protein of reconstituted cytochrome c oxidase.

The K(+)-ionophores valinomycin and nonactin induce a qualitatively identical change of the visible spectrum of isolated oxidized cytochrome c oxidase (red shift), but the amplitude is half with nonactin. Valinomycin, in the presence or absence of a protonophore, stimulates the respiration of the reconstituted enzyme to a higher extent than nonactin and results in a higher Km for cytochrome c. In contrast, nonactin causes a fivefold rate of proton conductivity across a liposomal membrane, after induction of a K(+)-diffusion potential. The data indicate that respiratory control by these antibiotics is not only due to degradation of a membrane potential, but rather to specific interaction with and modification of cytochrome c oxidase.

Animals↗
PubMed1990

Mutations of mitochondrial DNA and human death.

In the skeletal muscle of patients with mitochondrial myopathies (Kearns-Sayre syndrome and chronic progressive external ophthalmoplegia) and in the heart and skeletal muscle of healthy persons cells lacking cytochrome c oxidase are found. The respiratory-defective cells have the following features in common: onset of the defect at juvenile or adult age; progressive character of the defect with increasing age; and focal pattern of respiratory-deficient cells (fibers). A statistic mutation of mtDNA in affected cells is suggested to cause the defect of mitochondrial function. It is postulated that the continuous accumulation of respiratory-deficient cells, mainly in the human heart with increasing age, will finally limit the life-span of each human individual.

Animals↗
PubMed1990

Immunohistochemical demonstration of fibre type-specific isozymes of cytochrome c oxidase in human skeletal muscle.

The immunohistochemical reaction of monoclonal as well as polyclonal antibodies against cytochrome c oxidase (COX) subunits with serial sections of normal human skeletal muscle was investigated. The stronger reactivity of polyclonal antibodies to COX subunits II-III and VIIbc with type I as compared to type II fibres, correlated well with the higher histochemical reactivity of NADH dehydrogenase, succinate dehydrogenase and cytochrome c oxidase in type I fibres. In contrast an almost exclusive reaction of a monoclonal antibody against subunit IV with type I fibre and a preponderant reaction of a polyclonal antibody against subunits Vab with type II fibres was obtained. Antibodies against subunits I, Vb and VIc did not reveal a fibre-type-specific reactivity. The data indicate in human muscle the occurrence of fibre type-specific isozymes of cytochrome c oxidase differing in subunits IV and Va or Vb.

Antibodies, Monoclonal↗
PubMed1989

Influence of surface charge on the incorporation and orientation of cytochrome c oxidase in liposomes.

Cytochrome c-oxidase is usually oriented 80-90% right-side-out when reconstituted with asolectin by the cholate dialysis method. Transformation of positively charged lysine groups at the matrix domain into negatively charged groups with succinic anhydride results in random orientation. A random orientation is also found after reconstitution in phosphatidylcholine, which can be changed into predominant right-side-out orientation by addition of cardiolipin. It is concluded that electrostatic interaction between positively charged groups of cytochrome c-oxidase with negative groups of phospholipids determines the asymmetric orientation of the enzyme in liposomes.

Acetic Anhydrides↗
PubMed1989

Influence of non-esterified fatty acids on respiratory control of reconstituted cytochrome-c oxidase.

Bovine heart cytochrome-c oxidase was reconstituted in liposomes (asolectin) and the activity measured in the presence and absence of uncoupler at increasing concentrations of non-esterified fatty acids. Palmitic and stearic acids resulted in a decrease of about 40% in the respiratory control ratio at a concentration of 1 microM, when measured using a spectrophotometric procedure but not with a polarographic assay method. At higher fatty acid concentrations no further change was found. A 50% decrease in respiratory control was determined when the enzyme was reconstituted in pure phosphatidylcholine containing 2% cardiolipin. The respiratory control of reconstituted cytochrome-c oxidase from bovine liver was not influenced by fatty acids.

Animals↗
PubMed1989

A gene specifying subunit VIII of human cytochrome c oxidase is localized to chromosome 11 and is expressed in both muscle and non-muscle tissues.

Subunit VIII of mammalian cytochrome c oxidase (COX; EC 1.9.3.1) exists in at least two isoforms, because different but related polypeptides have been identified in COX isolated from liver and heart of both beef and pig. We have isolated a full length cDNA specifying subunit VIII of human COX from a human liver cDNA library. Sequences hybridizing to this cDNA are present at only one site, the COX8 locus, on human chromosome 11q12-q13. The deduced human polypeptide is 58% identical with COX VIII isolated from beef liver, but only 38% identical with COX VIII isolated from beef heart. Transcriptional analysis shows that an mRNA identical with the isolated cDNA is present in abundant amounts not only in human and monkey liver tissue, but in heart and skeletal muscle as well, tissues not known previously to contain this isoform. Since the only COX VIII subunit found in human heart agrees 100% with the polypeptide deduced from this coxVIII cDNA, it may well be that, in distinction to other mammals, only one form of COX VIII exists in primates.

Amino Acid Sequence↗
PubMed1989

Valinomycin binds stoichiometrically to cytochrome c oxidase and changes its structure and function.

Valinomycin binds to soluble and reconstituted cytochrome c oxidase (COX) in a stoichiometric manner, as shown by a spectral shift of the oxidized gamma-band. No spectral change is found with nigericin or 18-crown-6 and in the absence of potassium ions. Titration of the proton pumping activity of reconstituted COX with valinomycin reached a maximum of H+/e- - 0.73 after addition of 1 mole of valinomycin per mole of reconstituted COX. It is concluded that K+-translocation in proton-pumping COX vesicles occurs via enzyme-bound valinomycin.

Animals↗
PubMed1989

Cytochrome c oxidase deficiency in subacute necrotizing encephalopathy (Leigh syndrome).

Tissues and cultured fibroblasts from two patients with Leigh syndrome (subacute necrotizing encephalopathy) were examined. A systemic defect in cytochrome oxidase was identified by enzyme assay and estimation of cytochrome concentrations. Immunochemical analysis showed a reduction of most subunits of the cytochrome oxidase complex. The rate of synthesis of cytochrome oxidase subunits, determined by labelling experiments in cultured fibroblasts, was the same in the patients and normal controls. The reduced cytochrome oxidase content of the patients' tissues must therefore result from abnormal turnover of the protein subunits.

Animals↗
PubMed1989

Fatal mitochondrial myopathy with cytochrome-c-oxidase deficiency and subunit-restricted reduction of enzyme protein in two siblings: an autopsy-immunocytochemical study.

Lack of cytochrome-c oxidase activity and of cytochromes aa3 + b has been reported previously in the skeletal muscle of one of two siblings (Müller-Höcker et al, 1983). The present study reports a deficiency of immunoreactive enzyme protein in the skeletal muscle of both siblings, who had an identical fatal clinical course. In all specimens the defect did not involve the whole enzyme protein, but was selectively expressed in the mitochondrially derived subunits II/III and nuclear coded subunits VIIbc. Neither the specific fibers of the muscle spindles nor the mitochondria of the heart, liver, kidneys, vessel walls and/or gastrointestinal tract were affected. These results are most consistent with a primary nuclear defect being responsible for the organ specific and subunit selective expression of the enzyme defect.

Antibodies↗
PubMed1989

Immunocytochemical demonstration of cytochrome c oxidase as a marker for renal oncocytes and oncocytomas.

Using an antibody raised against the mitochondrial enzyme cytochrome c oxidase (EC 1.9.3.1), it was possible to visualize microoncocytomas, oncocytic tubules and even single oncocytes in the renal cortex of rats treated with N-nitrosomorpholine, and to localize the lesions to the collecting duct of the nephron. In human specimens, the antibody also stained oncocytomas and oncocytic tubules in the surrounding macroscopically unaffected cortex. Thus, this antibody may be used for detection as well as for investigation of the development of oncocytic lesions in various species.

Animals↗
PubMed1988

Anions induce conformational changes and influence the activity and photoaffinity-labelling by 8-azido-ATP of isolated cytochrome c oxidase.

The biphasic effect of anions on the activity of isolated bovine heart cytochrome c oxidase is paralleled by changes in the visible oxidized spectra, indicating the different conformational changes in the enzyme induced by bromide, chloride, sulphate, phosphate, ADP and ATP. Photoaffinity-labelling of most subunits of the isolated enzyme by low concentrations of 8-azido-[gamma-32P]ATP is strongly increased by ATP, ADP and unlabelled 8-azido-ATP in an unspecific manner. With the reconstituted enzyme less subunits are labelled and this labelling is only little affected by nucleotides. The data suggest a highly dynamic structure for isolated bovine heart cytochrome c oxidase.

Adenosine Triphosphate↗
PubMed1988

Intraliposomal nucleotides change the kinetics of reconstituted cytochrome c oxidase from bovine heart but not from Paracoccus denitrificans.

Isolated cytochrome c oxidases of P. denitrificans and bovine heart were reconstituted in liposomes and the kinetics of cytochrome c oxidation were measured in the presence and absence of nucleotides either inside or outside of proteoliposomes, and after photolabelling with 8-azido-ATP. Intraliposomal ATP increases and ADP decreases the kinetics of ferrocytochrome c oxidation of the bovine but not of the Paracoccus enzyme. Extra-liposomal ATP and ADP increase the Km for cytochrome c of both enzymes, but ATP acts at lower concentrations than ADP. The increase of the Km for cytochrome c is obtained in coupled as well as in uncoupled proteoliposomes. Photolabelling with 8-azido-ATP of the reconstituted Paracoccus enzyme also increases the Km for cytochrome c which is completely prevented if ATP but not if ADP is present during illumination as was found with reconstituted cytochrome c oxidase from bovine heart. The data suggest a specific interaction of ATP and ADP with nuclear-coded subunits of bovine heart cytochrome c oxidase from the matrix side, because the effects are not found with the Paracoccus enzyme, which lacks these subunits.

Adenine Nucleotides↗
PubMed1988

Characterization of two different genes (cDNA) for cytochrome c oxidase subunit VIa from heart and liver of the rat.

By antibody screening of a rat liver and a rat heart cDNA library in lambda gt11 two clones coding for the liver- and heart-specific subunit VIa of rat cytochrome c oxidase were isolated. In the heart cDNA sequence a TAA stop codon was found in frame 18 bp 5' upstream of the first methionine codon, thus excluding a leader sequence for this protein. The two cDNAs contain the full-length coding region of two subunits. The amino acid sequences of the two subunits show only 50% homology, whereas 74% homology was found between rat heart and bovine heart subunit VIa. By Northern blot analysis it is shown that the gene for subunit VIa from heart is only expressed in heart and skeletal muscle, whereas that from liver is also expressed in kidney, brain, heart and weakly in muscle.

Amino Acid Sequence↗
PubMed1988

Influence of 8-azido-ATP and other anions on the activity of cytochrome c oxidase.

The effect of ATP and other anions on the kinetics of cytochrome c oxidation by reconstituted bovine heart cytochrome c oxidase was investigated. The following results were obtained: (1) ATP and other polyvalent anions increase the Km for cytochrome c and the Vmax (if assayed by the photometric method). The magnitude of the effect is proportional to the charge of the anion as follows from the series of increasing effectiveness: Pi less than AMP less than ADP less than PPi less than ATP less than PPPi. (2) The kinetic effects are obtained in the millimolar physiological concentration range. (3) The kinetic changes are not saturated at high concentrations. (4) A specific interaction site for ATP at the cytosolic domain of the enzyme is concluded from the increase of Km for cytochrome c after photolabelling of proteoliposomes with 8-azido-[gamma-32P]-ATP, which is protected by ATP but not by ADP. (5) No specific "binding site" for ATP could be identified by photolabelling with 8-azido-[gamma-32P]-ATP. The labelling is only partly protected by ATP or ADP.

Adenine Nucleotides↗