K H Winterhalter

ETH Zurich, Zürich, ZH, Switzerland

Are you K H Winterhalter?

Claim your profile

Publications (185)860.66 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Laccase isozymes from the white-rot basidiomycete fungi Trametes versicolor and Pycnoporus cinnabarinus were purified to apparent iso-electric homogeneity and crystallised. T. versicolor laccase crystallises in two crystal forms, both with the orthorhombic space group P2(1)2(1)2(1), which diffract to 1.9 and 2.95 A resolution, respectively. The crystals of P. cinnabarinus laccase belong to the monoclinic space group C2 and diffract to at least 2.2 A resolution. All the laccase crystals are suitable for X-ray structure determination and contain a full complement of copper ions.
    Biochimica et Biophysica Acta 02/2002; 1594(1):109-14. · 4.66 Impact Factor
  • Source
    M F Bolliger, K Frei, K H Winterhalter, S M Gloor
    [Show abstract] [Hide abstract]
    ABSTRACT: Neuroligins, first discovered in rat brain, form a family of three synaptically enriched membrane proteins. Using reverse transcription-PCR of human brain polyadenylated RNA and extensive database searches, we identified the human homologues of the three rat neuroligins and a cDNA encoding a fourth member, which we named neuroligin 4. Neuroligin 4 has 63-73% amino acid identity with the other members of the human neuroligin family, and the same predicted domain structure. DNA database analyses, furthermore, indicated that a possible fifth neuroligin gene may be present in the human genome. Northern-blot analysis revealed expression of neuroligin 4 in heart, liver, skeletal muscle and pancreas, but barely at all in brain. Overexpression of neuroligin 4 cDNA in COS-7 cells led to the production of a 110 kDa protein. Immunofluorescence analysis demonstrated that the protein was integrated into the plasma membrane. Overexpression of cDNAs encoding neuroligin 4 and the PDZ-domain protein, PSD-95, in COS-7 cells resulted in the formation of detergent-resistant complexes. Neuroligin 4 did not bind to ZO-1, another PDZ-domain protein. Together, our data show that the human neuroligin family is composed of at least one additional member, and suggest that neuroligin 4 may also be produced outside the central nervous system.
    Biochemical Journal 07/2001; 356(Pt 2):581-8. · 4.65 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The crystal structure of affinity-purified Thermomonospora fusca beta-mannanase has been solved despite the lack of the major part of the amino-acid sequence. A high-quality electron-density map allowed the identification of a stretch of eight amino acids close to the C-terminus which was used to design a degenerate downstream PCR primer. Together with a specific primer previously derived from the N-terminus, 95.7% of the mannanase gene sequence was obtained from genomic T. fusca DNA by PCR. The structure-derived sequence was then compared with the DNA-derived sequence and corrected when necessary. Applying the presented protocol, there was no need to manually build a model at an early stage of structure determination, an erroneous and tedious process, especially in the absence of the amino-acid sequence. Using the DNA sequence information and the current version of ARP/wARP, 281 residues, or 93% of the polypeptide chain (including side chains), were built and refined to an R factor of 16.5% without any manual intervention.
    Acta Crystallographica Section D Biological Crystallography 02/2001; 57(Pt 1):37-43. · 14.10 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Organic anion transporting polypeptides (rodents: Oatps; human: OATPs) are involved in the absorption and elimination of a wide variety of structurally unrelated amphipathic organic compounds. Several members of this protein family mediate the uptake of substrates across the basolateral membrane of hepatocytes as the first step in hepatic elimination. In contrast to the well-characterized Oatp1 and Oatp2, the localization and substrate specificity of the recently cloned Oatp4 have not been investigated in detail. Therefore, we raised an antibody against the C-terminal end of Oatp4 and localized this 85-kDa protein to the basolateral membrane of rat hepatocytes. Similar to Oatp1 and Oatp2, Oatp4 is a multispecific transporter with high affinities for bromosulfophthalein, dehydroepiandrosterone sulfate, leukotriene C4, and anionic peptides. In addition, we compared the substrate specificity of Oatp4 to that of Oatp3, which so far has mainly been shown to mediate intestinal bile acid transport. Oatp3 had a similar broad substrate specificity, but in general much lower affinities than Oatp4. Thus, while Oatp4 seems to work in concert with Oatp1 and Oatp2 in the basolateral membrane of rat hepatocytes, Oatp3 is a multispecific transport system in the small intestine.
    Pflügers Archiv - European Journal of Physiology 01/2001; 443(2):188-195. · 4.87 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The crystal structure of affinity-purified Thermomonospora fuscaβ-mannanase has been solved despite the lack of the major part of the amino-acid sequence. A high-quality electron-density map allowed the identification of a stretch of eight amino acids close to the C-terminus which was used to design a degenerate downstream PCR primer. Together with a specific primer previously derived from the N-terminus, 95.7% of the mannanase gene sequence was obtained from genomic T. fusca DNA by PCR. The structure-derived sequence was then compared with the DNA-derived sequence and corrected when necessary. Applying the presented protocol, there was no need to manually build a model at an early stage of structure determination, an erroneous and tedious process, especially in the absence of the amino-acid sequence. Using the DNA sequence information and the current version of ARP/wARP, 281 residues, or 93% of the polypeptide chain (including side chains), were built and refined to an R factor of 16.5% without any manual intervention.
    Acta Crystallographica Section D Biological Crystallography 01/2001; 57(1):37-43. · 12.67 Impact Factor
  • Marc F. BOLLIGER, Karl FREI, Kaspar H. WINTERHALTER, Sergio M. GLOOR
    Biochemical Journal - BIOCHEM J. 01/2001; 356(2).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we identify the chondroitin sulfate proteoglycan versican V2 as a major inhibitor of axonal growth in the extracellular matrix of the mature central nervous system. In immunohistochemical and in situ hybridization experiments we show that this tissue-specific splice variant of versican is predominantly present in myelinated fiber tracts of the brain and in the optic nerve, most likely being expressed by oligodendrocytes. We demonstrate that isolated versican V2 strongly inhibits neurite outgrowth of central and peripheral neurons in stripe-choice assays using laminin-1 as permissive substrate. The inhibitory character of versican V2 is maintained after removal of chondroitin sulfate and N- and O-linked oligosaccharide side chains, but it is abolished after core protein digestion with proteinase-K. Our data support the notion, that intact versican V2 prevents excessive axonal growth during late phases of development and hereby participates in the structural stabilization of the mature central nervous system.
    Journal of Cell Science 04/2000; 113 ( Pt 5):807-16. · 5.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Regulation of epithelial and endothelial permeability is essential for proper function of compartmentalized organisms, and tyrosine phosphorylation plays an important role in this process. We analyzed the impact of protein tyrosine phosphatase (PTP) inhibition on the structure of endothelial junctional proteins. In human umbilical vein endothelial cells (HUVECs) the PTP inhibitors phenylarsine oxide (PAO) and pervanadate induced proteolysis of the tight junction protein occludin. Occludin proteolysis was inhibited by the metalloproteinase inhibitor 1,10-phenanthroline (PHEN), but not by inhibitors against other types of proteases. The junctional proteins ZO-1, cadherin and beta-catenin were not cleaved. Under conditions of occludin proteolysis, PAO treatment elevated permeability for FITC-dextran. Simultaneous incubation of HUVECs with PAO and PHEN inhibited the rise in permeability by more than 60%. PAO treatment lead to progressive disappearance of occludin from the cell periphery. In contrast, ZO-1, cadherin and beta-catenin retained their positions at the sites of intercellular contact. Simultaneous administration of PAO and PHEN greatly prevented the redistribution of occludin. These results demonstrate a selective cleavage of occludin by a metalloproteinase and suggest that this process can contribute to the control of paracellular permeability in endothelial cells.
    Journal of Cell Science 01/2000; 112 ( Pt 23):4347-56. · 5.88 Impact Factor
  • W Blodig, A T Smith, K Winterhalter, K Piontek
    [Show abstract] [Hide abstract]
    ABSTRACT: The heme enzyme lignin peroxidase contains a unique Cbeta-hydroxylated tryptophan residue (Trp171) on the surface of the enzyme. Mutagenetic substitution of Trp171 abolishes completely the veratryl alcohol oxidation activity of the enzyme. This led us to surmise that Trp171 may be involved in electron transfer from natural substrates to the heme cofactor. Here we present evidence for the formation of a transient radical on Trp171 using spin-trapping in combination with peptide mapping. The spin-trap methyl nitroso propane forms a covalent adduct with Trp171 in the presence of hydrogen peroxide which can be detected by its characteristic visible absorbance spectrum. A very similar chromophore can be obtained in a small molecular model system from N-acetyl tryptophanamide, the spin-trap, and a single-electron abstracting system. The precise site the spin-trap is attached to could be identified in a crystal structure of spin-trap/hydrogen peroxide-treated enzyme as the C6 atom of the indole ring of Trp171. These results indicate that Trp171 is redox-active and that it forms an indole radical by transfer of an electron to the heme of compound I and/or II. Apart from cytochrome c peroxidase and DNA photolyase, lignin peroxidase appears to be the third enzyme only which utilizes a tryptophan residue as an integral part of its redox catalysis.
    Archives of Biochemistry and Biophysics 11/1999; 370(1):86-92. · 3.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sterol carrier protein 2 (SCP2) is a basic intracellular protein which facilitates the in vitro intermembrane transfer of cholesterol, phospholipids and glycolipids. SCP2 was expressed in Escherichia coli, purified to apparent electrophoretic homogeneity and crystallized. Single crystals were obtained by hanging-drop vapour diffusion using ammonium sulfate as precipitant. These crystals belong to space group P4(1)2(1)2 or its enantiomorph, with unit-cell parameters a = b = 57.5, c = 86.5 A, and have one molecule in the crystallographic asymmetric unit. Intensity data to 1.8 A resolution were collected from native SCP2 crystals using synchrotron radiation, were processed and scaled with an R(linear) = 4.9%.
    Acta Crystallographica Section D Biological Crystallography 09/1999; 55(Pt 8):1478-80. · 14.10 Impact Factor
  • D Bisig, P Weber, L Vaughan, K H Winterhalter, K Piontek
    [Show abstract] [Hide abstract]
    ABSTRACT: A fragment of chicken tenascin consisting of fibronectin type-III domains 5 and 6 has been expressed in Escherichia coli. After modifying a previously reported purification protocol, an electrophoretically homogeneous recombinant protein was obtained from which various crystal forms could be grown under identical conditions. Only one form was suitable for structure determination. These crystals belong to space group P21, with unit-cell parameters a = 45.2, b = 57.9, c = 72.2 A, beta = 91.4 degrees, and diffract to at least 2.6 A resolution using synchrotron radiation. From density measurements of the crystals, it was found that there are two molecules in the asymmetric unit. Diffraction data of native, two platinum-derivative and one palladium-derivative crystals were collected.
    Acta Crystallographica Section D Biological Crystallography 06/1999; 55(Pt 5):1069-73. · 14.10 Impact Factor
  • T Choinowski, W Blodig, K H Winterhalter, K Piontek
    [Show abstract] [Hide abstract]
    ABSTRACT: The crystal structure of lignin peroxidase (LiP) from the white rot fungus Phanerochaete chrysosporium was refined to an R-factor of 16.2 % utilizing synchrotron data in the resolution range from 10 to 1.7 A. The final model comprises all 343 amino acid residues, 370 water molecules, the heme, four carbohydrates, and two calcium ions. Lignin peroxidase shows the typical peroxidase fold and the heme has a close environment as found in other peroxidases. During refinement of the LiP model an unprecedented modification of an amino acid was recognized. The surface residue tryptophan 171 in LiP is stereospecifically hydroxylated at the Cbeta atom due to an autocatalytic process. We propose that during the catalytic cycle of LiP a transient radical at Trp171 occurs that is different from those previously assumed for this type of peroxidase. Recently, the existence of a second substrate-binding site centered at Trp171 has been reported, by us which is different from the "classical heme edge" site found in other peroxidases. Here, we report evidence for a radical formation at Trp171 using spin trapping, which supports the concept of Trp171 being a redox active amino acid and being involved in the oxidation of veratryl alcohol. On the basis of our current model, an electron pathway from Trp171 to the heme is envisaged, relevant for the oxidation of veratryl alcohol and possibly lignin. Beside the opening leading to the heme edge, which can accommodate small aromatic substrate molecules, a smaller channel giving access to the distal heme pocket was identified that is large enough for molecules such as hydrogen peroxide. Furthermore, it was found that in LiP the bond between the heme iron and the Nepsilon2 atom of the proximal histidine residue is significantly longer than in cytochrome c peroxidase (CcP). The weaker Fe-N bond in LiP renders the heme more electron deficient and destabilizes high oxidation states, which could explain the higher redox potential of LiP as compared to CcP.
    Journal of Molecular Biology 03/1999; 286(3):809-27. · 3.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Descriptions for tenascin-C distribution are largely restricted to epithelial tumours. The present study utilized newly developed and characterized monoclonal (hT191) and polyclonal antibodies to investigate the distribution pattern of tenascin-C in a panel of mesenchymal tumours, which was contrasted with normal tissue. The specific antibodies recognized the distinctive star-like hexabrachion protein isolated from transformed cell-culture medium and serum from normal individuals. In normal tissues, a strong tenascin-C expression in the extracellular matrix was largely restricted to basement-membrane regions of epithelium and tonsilar sinusoids, pericellularly within smooth-muscle bundles, associated with perimysial, -chondrial, -neurial and -tendon surfaces, and diffusely within vascular adventitia. It was found in the corresponding tumours of the neural sheath (schwannoma) and smooth muscle (leiomyosarcoma), and was abundantly present around certain blood vessels of mesenchymal tumours. Although not detected in normal muscle, or in adipose or fibrous connective tissue, neo-expression of tenascin-C was shown in more than half of the rhabdomyosarcomas, fibromas and liposarcomas, with an increased positive percentage in variably malignant myxoid liposarcomas compared with lipoma-like sarcomas. Tenascin-C was typically found in the extracellular matrix of soft-tissue tumours, but was notably absent from the epithelial-cell components of mixed epithelial/mesenchymal tumours. Its apparently enhanced expression in soft-tissue tumours differs from that of most other large extracellular-matrix proteins, suggesting possible functional involvement of the cell-adhesion molecule, tenascin-C, in the neoplastic phenotype. Int. J. Cancer 72:217–224, 1997. © 1997 Wiley-Liss, Inc.
    International Journal of Cancer 12/1998; 72(2):217 - 224. · 6.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: . beta-Mannanases hydrolyse the O-glycosidic bonds in mannan, a hemicellulose constituent of plants. These enzymes have potential use in pulp and paper production and are of significant biotechnological interest. Thermostable beta-mannanases would be particularly useful due to their high temperature optimum and broad pH tolerance. The thermophilic actinomycete Thermomonospora fusca secretes at least one beta-mannanase (molecular mass 38 kDa) with a temperature optimum of 80 degreesC. No three-dimensional structure of a mannan-degrading enzyme has been reported until now. . The crystal structure of the thermostable beta-mannanase from T. fusca has been determined by the multiple isomorphous replacement method and refined to 1.5 A resolution. In addition to the native enzyme, the structures of the mannotriose- and mannohexaose-bound forms of the enzyme have been determined to resolutions of 1.9 A and 1.6 A, respectively. . Analysis of the -1 subsite of T. fusca mannanase reveals neither a favourable interaction towards the axial HO-C(2) nor a discrimination against the equatorial hydroxyl group of gluco-configurated substrates. We propose that selectivity arises from two possible mechanisms: a hydrophobic interaction of the substrate with Val263, conserved in family 5 bacterial mannanases, which discriminates between the different conformations of the hydroxymethyl group in native mannan and cellulose; and/or a specific interaction between Asp259 and the axial hydroxyl group at the C(2) of the substrate in the -2 subsite. Compared with the catalytic clefts of family 5 cellulases, the groove of T. fusca mannanase has a strongly reduced number of aromatic residues providing platforms for stacking with the substrate. This deletion of every second platform is in good agreement with the orientation of the axial hydroxyl groups in mannan.
    Structure 12/1998; 6(11):1433-44. · 5.99 Impact Factor
  • Source
    L Pontiggia, K Winterhalter, S M Gloor
    [Show abstract] [Hide abstract]
    ABSTRACT: cGMP has been shown to either activate or inhibit Na,K-ATPase activity. Using mouse brain endothelial cells which express both ouabain-resistant alpha1 and ouabain-sensitive alpha2 and alpha3 isoforms, we show that cGMP reduces total Na,KATPase activity to about 58%. The inhibition is prevented by the protein kinase G (PKG)-specific inhibitor KT5823, indicating that cGMP-mediated activation of PKG leads to inhibition of the pump. A similar extent of inhibition is obtained with nitric oxide. cGMP-induced inhibition acts mainly on alpha1 isoforms but hardly affects alpha2/alpha3 isoforms. These data suggest that inhibition of Na,K-ATPase activity by cGMP occurs in an isoform-selective manner in brain endothelial cells.
    FEBS Letters 11/1998; 436(3):466-70. · 3.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the high-resolution crystal structures of two lignin peroxidase isozymes from the white rot fungus Phanerochaete chrysosporium a significant electron density at single bond distance from the C beta of Trp171 was observed and interpreted as a hydroxy group. To further clarify the nature of this feature, we carried out tryptic digestion of the enzyme and isolated the Trp171 containing peptide. Under ambient conditions, this peptide shows an absorbance spectrum typical of tryptophan. At elevated temperature, however, the formation of an unusual absorbance spectrum with lambda max = 333 nm can be followed that is identical to that of N-acetyl-alpha, beta-didehydrotryptophanamide, resulting upon water elimination from beta-hydroxy tryptophan. The Trp171 containing tryptic peptide isolated from the recombinant and refolded lignin peroxidase produced from Escherichia coli does not contain the characteristic 333 nm absorbance band at any temperature. However, treatment with 3 equiv of H2O2 leads to complete hydroxylation of Trp171. Reducing substrates compete with this process, e.g., in the presence of 0.5 mM veratryl alcohol, about 7 equiv of H2O2 is necessary for complete modification. We conclude that the hydroxylation at the C beta of Trp171 is an autocatalytic reaction which occurs readily under conditions of natural turnover, e.g., in the ligninolytic cultures of P. chrysosporium, which are known to contain an oxidase-based H2O2-generating system. No dependence on dioxygen was found for this oxidative process. Chemical modification of fungal lignin peroxidase with the tryptophan-specific agent N-bromo succinimide leads to a drastically reduced activity with respect to the substrate veratryl alcohol. This suggests that Trp171 is involved in catalysis and that electron transfer from this surface residue to the oxidized heme cofactor is possible under steady-state conditions.
    Biochemistry 07/1998; 37(25):8832-8. · 3.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have isolated and characterized the proteoglycan isoforms of versican from bovine brain extracts. Our approach included (i) cDNA cloning and sequencing of the entire open reading frame encoding the bovine versican splice variants; (ii) preparation of antibodies against bovine versican using recombinant core protein fragments and synthetic peptides; (iii) isolation of versican isoforms by ammonium sulfate precipitation followed by anion exchange and hyaluronan affinity chromatography; and (iv) characterization by SDS-polyacrylamide gel electrophoresis and Coomassie Blue staining or immunoblotting. Our results demonstrate that versican V2 is, together with brevican, a major component of the mature brain extracellular matrix. Versicans V0 and V1 are only present in relatively small amounts. Versican V2 migrates after chondroitinase ABC digestion with an apparent molecular mass of about 400 kDa, whereas it barely enters a 4-15% polyacrylamide gel without the enzyme treatment. The 400-kDa product is recognized by antibodies against the glycosaminoglycan-alpha domain and against synthetic NH2- and COOH-terminal peptides. Our preparations contain no major proteolytic products of versican, e.g. hyaluronectin or glial hyaluronate-binding protein. Having biochemical quantities of versican V2 available will allow us to test its putative modulatory role in neuronal cell adhesion and axonal growth.
    Journal of Biological Chemistry 07/1998; 273(25):15758-64. · 4.65 Impact Factor
  • M U Kopp, K H Winterhalter, B Trueb
    [Show abstract] [Hide abstract]
    ABSTRACT: The expression of collagen VI, an adhesive glycoprotein of the extracellular matrix, is completely inhibited in virally transformed fibroblasts and in many cell lines derived from spontaneous mesenchymal tumors. Here we present evidence that DNA methylation plays an important role in this inhibition: (a) The mRNA level for DNA methyltransferase is highly increased in simian virus 40 (SV40)-transformed fibroblasts compared with normal cells and this increase correlates with the decrease of the mRNA level for collagen VI. (b) Methylation of the alpha2(VI) collagen promoter in vitro abolishes promoter activity in a transient transfection assay. (c) Genomic sequencing reveals extensive methylation of the promoter region in SV40-transformed cells, but virtually no methylation of the corresponding region in normal cells. Increased methylation is also observed in a rhabdomyosarcoma cell line. (d) Two of the cis-acting elements of the alpha2(VI) collagen promoter lose their affinity for transcription factor AP2 when methylated in vitro as demonstrated by gel retardation experiments. DNA methylation is therefore involved in the silencing of the alpha2(VI) collagen gene. It seems likely that the same mechanism is also responsible for the repression of other transformation-sensitive proteins.
    European Journal of Biochemistry 11/1997; 249(2):489-96. · 3.58 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Descriptions for tenascin-C distribution are largely restricted to epithelial tumours. The present study utilized newly developed and characterized monoclonal (hT191) and polyclonal antibodies to investigate the distribution pattern of tenascin-C in a panel of mesenchymal tumours, which was contrasted with normal tissue. The specific antibodies recognized the distinctive star-like hexabrachion protein isolated from transformed cell-culture medium and serum from normal individuals. In normal tissues, a strong tenascin-C expression in the extracellular matrix was largely restricted to basement-membrane regions of epithelium and tonsilar sinusoids, pericellularly within smooth-muscle bundles, associated with perimysial, -chondrial, -neurial and -tendon surfaces, and diffusely within vascular adventitia. It was found in the corresponding tumours of the neural sheath (schwannoma) and smooth muscle (leiomyosarcoma), and was abundantly present around certain blood vessels of mesenchymal tumours. Although not detected in normal muscle, or in adipose or fibrous connective tissue, neo-expression of tenascin-C was shown in more than half of the rhabdomyosarcomas, fibromas and liposarcomas, with an increased positive percentage in variably malignant myxoid liposarcomas compared with lipoma-like sarcomas. Tenascin-C was typically found in the extracellular matrix of soft-tissue tumours, but was notably absent from the epithelial-cell components of mixed epithelial/mesenchymal tumours. Its apparently enhanced expression in soft-tissue tumours differs from that of most other large extracellular-matrix proteins, suggesting possible functional involvement of the cell-adhesion molecule, tenascin-C, in the neoplastic phenotype.
    International Journal of Cancer 08/1997; 72(2):217-24. · 6.20 Impact Factor
  • J P Silva, K H Winterhalter, C Richter
    [Show abstract] [Hide abstract]
    ABSTRACT: Rat liver mitochondria have a specific Ca2+ release pathway which operates when NAD+ is hydrolysed to nicotinamide and ADPribose. NAD+ hydrolysis is Ca(2+)-dependent and inhibited by cyclosporine A (CSA). Mitochondrial Ca2+ release can be activated by the prooxidant t-butylhydroperoxide (tbh) or by gliotoxin (GT), a fungal metabolite of the epipolythiodioxopiperazine group. Tbh oxidizes NADH to NAD+ through an enzyme cascade consisting of glutathione peroxidase, glutathione reductase, and the energy linked transhydrogenase, whereas GT oxidizes some vicinal thiols to the disulfide form, a prerequisite for NAD+ hydrolysis. We report now that rat skeletal muscle mitochondria also contain a specific Ca2+ release pathway activated by both tbh and GT. Ca2+ release increases with the mitochondrial Ca2+ load, is completely inhibited in the presence of CSA, and is paralleled by pyridine nucleotide oxidation. In the presence of tbh and GT, mitochondria do not lose their membrane potential and do not swell, provided continuous release and re-uptake of Ca2+ ('Ca2+ cycling') is prevented. These data support the notion that both tbh- and GT-induced Ca2+ release are not the consequence of an unspecific increase of the inner membrane permeability ('pore' formation). Tbh induces Ca2+ release from rat skeletal muscle less efficiently than from liver mitochondria indicating that the coupling between tbh and NADH oxidation is much weaker in skeletal muscle mitochondria. This conclusion is corroborated by a much lower glutathione peroxidase activity in skeletal muscle than in liver mitochondria. The prooxidant-dependent pathway promotes, under drastic conditions (high mitochondrial Ca2+ loads and high tbh concentrations), Ca2+ release to about the same extent and rate as the Na+/Ca2+ exchanger. This renders the prooxidant-dependent pathway relevant in the pathophysiology of mitochondrial myopathies where its activation by an increased generation of reactive oxygen species probably results in excessive Ca2+ cycling and damage to mitochondria.
    Redox Report 01/1997; 3(5-6):331-41. · 1.66 Impact Factor

Publication Stats

4k Citations
860.66 Total Impact Points

Institutions

  • 1985–2001
    • ETH Zurich
      • • Institute of Biochemistry
      • • Laboratory of Organic Chemistry
      Zürich, ZH, Switzerland
  • 1985–2000
    • University of Zurich
      • Institute of Virology
      Zürich, Zurich, Switzerland
  • 1983–2000
    • Eawag: Das Wasserforschungs-Institut des ETH-Bereichs
      Duebendorf, Zurich, Switzerland
  • 1979–1999
    • Hochschule für Technik Zürich
      Zürich, Zurich, Switzerland
  • 1985–1998
    • École Polytechnique Fédérale de Lausanne
      • Laboratoire de chimie et biochimie computationnelles
      Lausanne, VD, Switzerland
  • 1994
    • Università degli Studi di Palermo
      Palermo, Sicily, Italy
  • 1991
    • University of Illinois, Urbana-Champaign
      Urbana, Illinois, United States
    • The University of Tokyo
      • College of Art and Science & Graduate School of Arts and Sciences
      Tokyo, Tokyo-to, Japan
  • 1988
    • National Institute for Food and Nutrition Science
      Budapeŝto, Budapest, Hungary
  • 1976
    • University of Cambridge
      • Department of Clinical Biochemistry
      Cambridge, ENG, United Kingdom
    • Friedrich Miescher Institute for Biomedical Research
      Bâle, Basel-City, Switzerland
  • 1972
    • The American Society for Biochemistry and Molecular Biology
      Rome, New York, United States
  • 1970
    • Istituto Regina Elena - Istituti Fisioterapici Ospitalieri
      Roma, Latium, Italy
  • 1969
    • University of Washington Seattle
      • Department of Medicine
      Seattle, Washington, United States