The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform
Wolfram Kress - One of the best experts on this subject based on the ideXlab platform.
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ocular ochronosis in alkaptonuria patients carrying mutations in the Homogentisate 1 2 dioxygenase gene
British Journal of Ophthalmology, 1999Co-Authors: Ute Felbor, C R Muller, Yvonne Mutsch, Franz Grehn, Wolfram KressAbstract:AIMS—To assess the involvement of the recently identified human Homogentisate 1,2-dioxygenase gene (HGO) in alkaptonuria (AKU) in two unrelated patients with ochronosis of the conjunctiva, sclera, and cornea. METHODS—A mutation screen of the entire coding region of the HGO gene was performed using single stranded conformational analysis after polymerase chain reaction with oligonucleotide primers flanking all 14 exons of the HGO gene. Fragments showing aberrant mobility were directly sequenced. RESULTS—Two homozygous missense mutations, L25P and M368V, were identified, each of which leads to the replacement of a highly conserved amino acid in the HGO protein. CONCLUSIONS—The authors describe a novel mutation, L25P, in the German population and bring to 18 the total number of known HGO mutations.
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murine liver Homogentisate 1 2 dioxygenase
FEBS Journal, 1995Co-Authors: S Schmidt, C R Muller, Wolfram KressAbstract:1 The murine liver enzyme homogenisate 1,2-dioxygenase (HGO) is purified 330–fold. The molecular mass, as determined by gel filtration, is approximately 149 kDa. SDS/PAGE under strongly reducing conditions reveals a single band at 49 kDa, whose concentration increases during the purification. 2 HGO has a pI = 8. The pH optimum for activity in vitro is 6.1. 3 The Km for its natural substrate HGA is 188 μM, whereas the Kd for the ferrous ion is determined at 19 μM. Fe2+ is an absolutely obligate cofactor and cannot be replaced by other divalent cations. Incubating the enzyme with Fe2+ plus one of other divalent cations Zn2+, Cu2+, Co2+ or Ni2+ in equimolar concentrations inhibits HGO, whereas addition of Ca2+ and Mn2+ has no effect. Ascorbate probably acts as a reducing agent, protecting Fe2+ from spontaneous oxidation or by reversing its oxidation. Ascorbate has a great potential to stabilize the assay system. 4 The activation energy determined by an Arrhenius plot is 24 kJ/mol. 5 HGO consists of a single type of subunit with no intermolecular disulfide bridges and requires Fe2+ as a cofactor. This emphazises that the enzyme is familiar with the class of extradiol dioxygenases.
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murine liver Homogentisate 1 2 dioxygenase purification to homogeneity and novel biochemical properties
FEBS Journal, 1995Co-Authors: S Schmidt, C R Muller, Wolfram KressAbstract:1. The murine liver enzyme homogenisate 1,2-dioxygenase (HGO) is purified 330-fold. The molecular mass, as determined by gel filtration, is approximately 149 kDa. SDS/PAGE under strongly reducing conditions reveals a single band at 49 kDa, whose concentration increases during the purification. 2. HGO has a pI = 8. The pH optimum for activity in vitro is 6.1. 3. The Km for its natural substrate HGA is 188 microM, whereas the Kd for the ferrous ion is determined at 19 microM. Fe2+ is an absolutely obligate cofactor and cannot be replaced by other divalent cations. Incubating the enzyme with Fe2+ plus one of other divalent cations Zn2+, Cu2+, Co2+ or Ni2+ in equimolar concentrations inhibits HGO, whereas addition of Ca2+ and Mn2+ has no effect. Ascorbate probably acts as a reducing agent, protecting Fe2+ from spontaneous oxidation or by reversing its oxidation. Ascorbate has a great potential to stabilize the assay system. 4. The activation energy determined by an Arrhenius plot is 24 kJ/mol. 5. HGO consists of a single type of subunit with no intermolecular disulfide bridges and requires Fe2+ as a cofactor. This emphazises that the enzyme is familiar with the class of extradiol dioxygenases.
Jim Manos - One of the best experts on this subject based on the ideXlab platform.
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Homogentisate 1-2-Dioxygenase Downregulation in the Chronic Persistence of Pseudomonas aeruginosa Australian Epidemic Strain-1 in the CF Lung
PloS one, 2015Co-Authors: Christopher J. Harmer, Matthew T. Wynn, Rachel Pinto, Stuart J. Cordwell, Barbara Rose, Colin Harbour, James A. Triccas, Jim ManosAbstract:Some Pseudomonas aeruginosa strains including Australian Epidemic Strain-1 (AES-1 or AUS-01) cause persistent chronic infection in cystic fibrosis (CF) patients, with greater morbidity and mortality. Factors conferring persistence are largely unknown. Previously we analysed the transcriptomes of AES-1 grown in Luria broth, nematode growth medium for Caenorhabditis elegans assay (both aerobic) and artificial sputum medium (mainly hypoxic). Transcriptional comparisons included chronic AES-1 strains against PAO1 and acute AES-1 (AES-1R) against its chronic isogen (AES-1M), isolated 10.5 years apart from a CF patient and not eradicated in the meantime. Prominent amongst genes downregulated in AES-1M in all comparisons was Homogentisate-1-2-dioxygenase (hmgA); an oxygen-dependent gene known to be mutationally deactivated in many chronic infection strains of P. aeruginosa. To investigate if hmgA downregulation and deactivation gave similar virulence persistence profiles, a hmgA mutant made in UCBPP-PA14 utilising RedS-recombinase and AES-1M were assessed in the C. elegans virulence assay, and the C57BL/6 mouse for pulmonary colonisation and TNF-α response. In C. elegans, hmgA deactivation resulted in significantly increased PA14 virulence while hmgA downregulation reduced AES-1M virulence. AES-1M was significantly more persistent in mouse lung and showed a significant increase in TNF-α (p
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Homogentisate 1 2 dioxygenase downregulation in the chronic persistence of pseudomonas aeruginosa australian epidemic strain 1 in the cf lung
PLOS ONE, 2015Co-Authors: Christopher J. Harmer, Rachel Pinto, Stuart J. Cordwell, Barbara Rose, Colin Harbour, James A. Triccas, Matthew Wynn, Jim ManosAbstract:Some Pseudomonas aeruginosa strains including Australian Epidemic Strain-1 (AES-1 or AUS-01) cause persistent chronic infection in cystic fibrosis (CF) patients, with greater morbidity and mortality. Factors conferring persistence are largely unknown. Previously we analysed the transcriptomes of AES-1 grown in Luria broth, nematode growth medium for Caenorhabditis elegans assay (both aerobic) and artificial sputum medium (mainly hypoxic). Transcriptional comparisons included chronic AES-1 strains against PAO1 and acute AES-1 (AES-1R) against its chronic isogen (AES-1M), isolated 10.5 years apart from a CF patient and not eradicated in the meantime. Prominent amongst genes downregulated in AES-1M in all comparisons was Homogentisate-1-2-dioxygenase (hmgA); an oxygen-dependent gene known to be mutationally deactivated in many chronic infection strains of P. aeruginosa. To investigate if hmgA downregulation and deactivation gave similar virulence persistence profiles, a hmgA mutant made in UCBPP-PA14 utilising RedS-recombinase and AES-1M were assessed in the C. elegans virulence assay, and the C57BL/6 mouse for pulmonary colonisation and TNF-α response. In C. elegans, hmgA deactivation resulted in significantly increased PA14 virulence while hmgA downregulation reduced AES-1M virulence. AES-1M was significantly more persistent in mouse lung and showed a significant increase in TNF-α (p<0.0001), sustained even with no detectable bacteria. PA14ΔhmgA did not show increased TNF-α. This study suggests that hmgA may have a role in P. aeruginosa persistence in chronic infection and the results provide a starting point for clarifying the role of hmgA in chronic AES-1.
C R Muller - One of the best experts on this subject based on the ideXlab platform.
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ocular ochronosis in alkaptonuria patients carrying mutations in the Homogentisate 1 2 dioxygenase gene
British Journal of Ophthalmology, 1999Co-Authors: Ute Felbor, C R Muller, Yvonne Mutsch, Franz Grehn, Wolfram KressAbstract:AIMS—To assess the involvement of the recently identified human Homogentisate 1,2-dioxygenase gene (HGO) in alkaptonuria (AKU) in two unrelated patients with ochronosis of the conjunctiva, sclera, and cornea. METHODS—A mutation screen of the entire coding region of the HGO gene was performed using single stranded conformational analysis after polymerase chain reaction with oligonucleotide primers flanking all 14 exons of the HGO gene. Fragments showing aberrant mobility were directly sequenced. RESULTS—Two homozygous missense mutations, L25P and M368V, were identified, each of which leads to the replacement of a highly conserved amino acid in the HGO protein. CONCLUSIONS—The authors describe a novel mutation, L25P, in the German population and bring to 18 the total number of known HGO mutations.
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murine liver Homogentisate 1 2 dioxygenase
FEBS Journal, 1995Co-Authors: S Schmidt, C R Muller, Wolfram KressAbstract:1 The murine liver enzyme homogenisate 1,2-dioxygenase (HGO) is purified 330–fold. The molecular mass, as determined by gel filtration, is approximately 149 kDa. SDS/PAGE under strongly reducing conditions reveals a single band at 49 kDa, whose concentration increases during the purification. 2 HGO has a pI = 8. The pH optimum for activity in vitro is 6.1. 3 The Km for its natural substrate HGA is 188 μM, whereas the Kd for the ferrous ion is determined at 19 μM. Fe2+ is an absolutely obligate cofactor and cannot be replaced by other divalent cations. Incubating the enzyme with Fe2+ plus one of other divalent cations Zn2+, Cu2+, Co2+ or Ni2+ in equimolar concentrations inhibits HGO, whereas addition of Ca2+ and Mn2+ has no effect. Ascorbate probably acts as a reducing agent, protecting Fe2+ from spontaneous oxidation or by reversing its oxidation. Ascorbate has a great potential to stabilize the assay system. 4 The activation energy determined by an Arrhenius plot is 24 kJ/mol. 5 HGO consists of a single type of subunit with no intermolecular disulfide bridges and requires Fe2+ as a cofactor. This emphazises that the enzyme is familiar with the class of extradiol dioxygenases.
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murine liver Homogentisate 1 2 dioxygenase purification to homogeneity and novel biochemical properties
FEBS Journal, 1995Co-Authors: S Schmidt, C R Muller, Wolfram KressAbstract:1. The murine liver enzyme homogenisate 1,2-dioxygenase (HGO) is purified 330-fold. The molecular mass, as determined by gel filtration, is approximately 149 kDa. SDS/PAGE under strongly reducing conditions reveals a single band at 49 kDa, whose concentration increases during the purification. 2. HGO has a pI = 8. The pH optimum for activity in vitro is 6.1. 3. The Km for its natural substrate HGA is 188 microM, whereas the Kd for the ferrous ion is determined at 19 microM. Fe2+ is an absolutely obligate cofactor and cannot be replaced by other divalent cations. Incubating the enzyme with Fe2+ plus one of other divalent cations Zn2+, Cu2+, Co2+ or Ni2+ in equimolar concentrations inhibits HGO, whereas addition of Ca2+ and Mn2+ has no effect. Ascorbate probably acts as a reducing agent, protecting Fe2+ from spontaneous oxidation or by reversing its oxidation. Ascorbate has a great potential to stabilize the assay system. 4. The activation energy determined by an Arrhenius plot is 24 kJ/mol. 5. HGO consists of a single type of subunit with no intermolecular disulfide bridges and requires Fe2+ as a cofactor. This emphazises that the enzyme is familiar with the class of extradiol dioxygenases.
S Schmidt - One of the best experts on this subject based on the ideXlab platform.
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murine liver Homogentisate 1 2 dioxygenase
FEBS Journal, 1995Co-Authors: S Schmidt, C R Muller, Wolfram KressAbstract:1 The murine liver enzyme homogenisate 1,2-dioxygenase (HGO) is purified 330–fold. The molecular mass, as determined by gel filtration, is approximately 149 kDa. SDS/PAGE under strongly reducing conditions reveals a single band at 49 kDa, whose concentration increases during the purification. 2 HGO has a pI = 8. The pH optimum for activity in vitro is 6.1. 3 The Km for its natural substrate HGA is 188 μM, whereas the Kd for the ferrous ion is determined at 19 μM. Fe2+ is an absolutely obligate cofactor and cannot be replaced by other divalent cations. Incubating the enzyme with Fe2+ plus one of other divalent cations Zn2+, Cu2+, Co2+ or Ni2+ in equimolar concentrations inhibits HGO, whereas addition of Ca2+ and Mn2+ has no effect. Ascorbate probably acts as a reducing agent, protecting Fe2+ from spontaneous oxidation or by reversing its oxidation. Ascorbate has a great potential to stabilize the assay system. 4 The activation energy determined by an Arrhenius plot is 24 kJ/mol. 5 HGO consists of a single type of subunit with no intermolecular disulfide bridges and requires Fe2+ as a cofactor. This emphazises that the enzyme is familiar with the class of extradiol dioxygenases.
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murine liver Homogentisate 1 2 dioxygenase purification to homogeneity and novel biochemical properties
FEBS Journal, 1995Co-Authors: S Schmidt, C R Muller, Wolfram KressAbstract:1. The murine liver enzyme homogenisate 1,2-dioxygenase (HGO) is purified 330-fold. The molecular mass, as determined by gel filtration, is approximately 149 kDa. SDS/PAGE under strongly reducing conditions reveals a single band at 49 kDa, whose concentration increases during the purification. 2. HGO has a pI = 8. The pH optimum for activity in vitro is 6.1. 3. The Km for its natural substrate HGA is 188 microM, whereas the Kd for the ferrous ion is determined at 19 microM. Fe2+ is an absolutely obligate cofactor and cannot be replaced by other divalent cations. Incubating the enzyme with Fe2+ plus one of other divalent cations Zn2+, Cu2+, Co2+ or Ni2+ in equimolar concentrations inhibits HGO, whereas addition of Ca2+ and Mn2+ has no effect. Ascorbate probably acts as a reducing agent, protecting Fe2+ from spontaneous oxidation or by reversing its oxidation. Ascorbate has a great potential to stabilize the assay system. 4. The activation energy determined by an Arrhenius plot is 24 kJ/mol. 5. HGO consists of a single type of subunit with no intermolecular disulfide bridges and requires Fe2+ as a cofactor. This emphazises that the enzyme is familiar with the class of extradiol dioxygenases.
Christopher J. Harmer - One of the best experts on this subject based on the ideXlab platform.
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Homogentisate 1-2-Dioxygenase Downregulation in the Chronic Persistence of Pseudomonas aeruginosa Australian Epidemic Strain-1 in the CF Lung
PloS one, 2015Co-Authors: Christopher J. Harmer, Matthew T. Wynn, Rachel Pinto, Stuart J. Cordwell, Barbara Rose, Colin Harbour, James A. Triccas, Jim ManosAbstract:Some Pseudomonas aeruginosa strains including Australian Epidemic Strain-1 (AES-1 or AUS-01) cause persistent chronic infection in cystic fibrosis (CF) patients, with greater morbidity and mortality. Factors conferring persistence are largely unknown. Previously we analysed the transcriptomes of AES-1 grown in Luria broth, nematode growth medium for Caenorhabditis elegans assay (both aerobic) and artificial sputum medium (mainly hypoxic). Transcriptional comparisons included chronic AES-1 strains against PAO1 and acute AES-1 (AES-1R) against its chronic isogen (AES-1M), isolated 10.5 years apart from a CF patient and not eradicated in the meantime. Prominent amongst genes downregulated in AES-1M in all comparisons was Homogentisate-1-2-dioxygenase (hmgA); an oxygen-dependent gene known to be mutationally deactivated in many chronic infection strains of P. aeruginosa. To investigate if hmgA downregulation and deactivation gave similar virulence persistence profiles, a hmgA mutant made in UCBPP-PA14 utilising RedS-recombinase and AES-1M were assessed in the C. elegans virulence assay, and the C57BL/6 mouse for pulmonary colonisation and TNF-α response. In C. elegans, hmgA deactivation resulted in significantly increased PA14 virulence while hmgA downregulation reduced AES-1M virulence. AES-1M was significantly more persistent in mouse lung and showed a significant increase in TNF-α (p
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Homogentisate 1 2 dioxygenase downregulation in the chronic persistence of pseudomonas aeruginosa australian epidemic strain 1 in the cf lung
PLOS ONE, 2015Co-Authors: Christopher J. Harmer, Rachel Pinto, Stuart J. Cordwell, Barbara Rose, Colin Harbour, James A. Triccas, Matthew Wynn, Jim ManosAbstract:Some Pseudomonas aeruginosa strains including Australian Epidemic Strain-1 (AES-1 or AUS-01) cause persistent chronic infection in cystic fibrosis (CF) patients, with greater morbidity and mortality. Factors conferring persistence are largely unknown. Previously we analysed the transcriptomes of AES-1 grown in Luria broth, nematode growth medium for Caenorhabditis elegans assay (both aerobic) and artificial sputum medium (mainly hypoxic). Transcriptional comparisons included chronic AES-1 strains against PAO1 and acute AES-1 (AES-1R) against its chronic isogen (AES-1M), isolated 10.5 years apart from a CF patient and not eradicated in the meantime. Prominent amongst genes downregulated in AES-1M in all comparisons was Homogentisate-1-2-dioxygenase (hmgA); an oxygen-dependent gene known to be mutationally deactivated in many chronic infection strains of P. aeruginosa. To investigate if hmgA downregulation and deactivation gave similar virulence persistence profiles, a hmgA mutant made in UCBPP-PA14 utilising RedS-recombinase and AES-1M were assessed in the C. elegans virulence assay, and the C57BL/6 mouse for pulmonary colonisation and TNF-α response. In C. elegans, hmgA deactivation resulted in significantly increased PA14 virulence while hmgA downregulation reduced AES-1M virulence. AES-1M was significantly more persistent in mouse lung and showed a significant increase in TNF-α (p<0.0001), sustained even with no detectable bacteria. PA14ΔhmgA did not show increased TNF-α. This study suggests that hmgA may have a role in P. aeruginosa persistence in chronic infection and the results provide a starting point for clarifying the role of hmgA in chronic AES-1.