Search results for "DEHYDROGENASE COMPLEX"

2017

Previous studies reported that the use of Metschnikowia pulcherrima in sequential culture fermentation with Saccharomyces cerevisiae mainly induced a reduction of volatile acidity in wine. The impact of the presence of this yeast on the metabolic pathway involved in pyruvate dehydrogenase (PDH) bypass and glycerol production in S. cerevisiae has never been investigated. In this work, we compared acetic acid and glycerol production kinetics between pure S. cerevisiae culture and its sequential culture with M. pulcherrima during alcoholic fermentation. In parallel, the expression levels of the principal genes involved in PDH bypass and glyceropyruvic fermentation in S. cerevisiae were investi…

2019

Mitochondria have been increasingly recognized as a central regulatory nexus for multiple metabolic pathways, in addition to ATP production via oxidative phosphorylation (OXPHOS). Here we show that inducing mitochondrial DNA (mtDNA) stress in Drosophila using a mitochondrially-targeted Type I restriction endonuclease (mtEcoBI) results in unexpected metabolic reprogramming in adult flies, distinct from effects on OXPHOS. Carbohydrate utilization was repressed, with catabolism shifted towards lipid oxidation, accompanied by elevated serine synthesis. Cleavage and translocation, the two modes of mtEcoBI action, repressed carbohydrate rmetabolism via two different mechanisms. DNA cleavage activ…

Autoreactive liver-infiltrating T cells in primary biliary cirrhosis recognize inner mitochondrial epitopes and the pyruvate dehydrogenase complex.

1993

Primary biliary cirrhosis (PBC) is characterized by lymphoid infiltrates in the portal tracts of the liver and the occurrence of antimitochondrial autoantibodies in serum directed against components of the pyruvate dehydrogenase complex and the other alpha-keto acid dehydrogenase complexes. These enzymes are located on the inner mitochondrial membrane. The destruction of the biliary tract in PBC is thought to be mediated by autoreactive liver-infiltrating T cells exerting cytotoxic activity or releasing certain lymphokines. In this study the reactivity of liver infiltrating T cells was shown to a bovine pyruvate dehydrogenase complex (PDH), a purified E2 subunit (PDH-E2) and a crude prepara…

Immunoblotting as a confirmatory test for antimitochondrial antibodies in primary biliary cirrhosis.

1993

Primary biliary cirrhosis is characterised by the presence of antimitochondrial antibodies which are directed against components of mitochondrial dehydrogenase complexes. The specificity of antimitochondrial antibodies for primary biliary cirrhosis as detected by immunoblotting was investigated. Commercially available preparations of pyruvate and oxo-glutarate dehydrogenases and beef-heart mitochondria were used as source of antigens. Sera from 47 primary biliary cirrhosis patients (46 of whom were antimitochondrial antibody positive by immunofluorescence), 16 non-primary biliary cirrhosis patients (antimitochondrial antibody positive by immunofluorescence), 23 liver-kidney microsomal antib…

Pyruvate dehydrogenase specific T cells in primary biliary cirrhosis show restricted antigen recognition sites

2002

:  Background/Aims: The aim was to characterise the antigen recognition sites of the variable T cell receptor α-chain (TCRAV) and β-chain (TCRBV) of T cells specific to the pyruvate dehydrogenase (PDC) in primary biliary cirrhosis. Methods: In 21 PDC-specific T cell clones isolated from five patients we analysed TCRAV and TCRBV usage by RT-PCR and sequenced the CDR3 regions. Results: Preferential expression of the TCR elements BV6 (6 clones), BV12 (4 clones) and BV1 (3 clones), and frequent usage of the joining elements JB2.3 and JB2.1 were seen. Analysis of the α chain revealed rearrangement of AV2 in 7 clones (35%) and AV7 in 3 clones, however, distribution of the joining elements was het…

Kinetics of lactate fermentation and citrate bioconversion by LactococcusIactisssp.Iactisin batch culture

1993

The growth kinetics of Lactococcus lactis ssp. lactis were studied in batch culture in conditions of non-limiting lactose and the presence of citric acid. The control of pH modified growth and citrate metabolism but did not change the yield of acid formation. At controlled pH the growth rate was unaffected by citrate metabolism. Lactose was transformed to L-lactate and assay of the metabolic by-products showed some heterofermentation at the end of the growth of cultures with low growth rates. This heterofermentation was interpreted as a slowing down of glycolysis with activation of both the pyruvate formate lyase (PFL) and the pyruvate dehydrogenase complex (PDHC). Under these conditions th…

Leigh syndrome due to compound heterozygosity of dihydrolipoamide dehydrogenase gene mutations. Description of the first E3 splice site mutation.

2003

Item does not contain fulltext A boy with recurrent episodes of hypoglycaemia and ataxia, microcephaly, mental retardation, permanent lactic acidaemia, intermittent 2-oxoglutaric aciduria as well as elevation of serum branched chain amino acids was diagnosed with dihydrolipoamide dehydrogenase (E3) deficiency. Analysis of genomic DNA revealed compound heterozygosity for two novel mutations: I393T in exon 11, located at the interface domain of the protein and possibly interfering with its dimerisation, and IVS9+1G>A located at a consensus splice site. A heterozygous polymorphism was also detected. In the patient's cDNA the I393T mutation and the polymorphism appeared to be homozygous, indica…

Abnormalities of mitochondrial functioning can partly explain the metabolic disorders encountered in sarcopenic gastrocnemius.

2007

International audience; Aging triggers several abnormalities in muscle glycolytic fibers including increased proteolysis, reactive oxygen species (ROS) production and apoptosis. Since the mitochondria are the main site of substrate oxidation, ROS production and programmed cell death, we tried to know whether the cellular disorders encountered in sarcopenia are due to abnormal mitochondrial functioning. Gastrocnemius mitochondria were extracted from adult (6 months) and aged (21 months) male Wistar rats. Respiration parameters, opening of the permeability transition pore and ROS production, with either glutamate (amino acid metabolism) or pyruvate (glucose metabolism) as a respiration substr…

Electron transport chain in aerobically cultivated Zymomonas mobilis

1996

Respiratory chain composition and energy coupling in cytoplasmic membrane of Zymomonas mobilis was shown to depend on culture aeration. Aerobically grown cells contained mainly the non-energy-generating NADH dehydrogenase with kM for NADH 58 mM. In anaerobically cultivated bacteria, the energy-coupling NADH dehydrogenase complex with km for NADH 7 mM predominated. In aerobically cultivated Z. mobilis, CoQ content and absorption peaks of cytochromes at 554–556 nm and 525–528 nm were significantly increased. Energy-coupling site I, linked to the NADH:CoQ oxidoreductase complex, could be eliminated under sulfate-deficient cultivation conditions. For anaerobically grown cells this resulted in l…

Influence of carboxylic acids on the stereospecific nicotinamide adenine dinucleotide-dependent and nicotinamide adenine dinucleotide-independent lac…

1971

Leuconostoc mesenteroides increased its lactic acid production from glucose threefold when malic acid was added to the culture. This increase resulted also in a reduction of the ratio of d -lactic acid to l -lactic acid (31.5 to 1.23). Addition of malic acid increased 6.5-fold the specific activity of nicotinamide adenine dinucleotide (NAD)-linked l -lactate dehydrogenase and increased 3.2-fold that of NAD-linked d -lactate dehydrogenase. The Michaelis constant ( K m ) for NAD of the NAD-linked l -lactate dehydrogenase increased with the addition of malate, but no change was observed in the K m values for the respective d -enzyme. The effect of carboxylic acids on the NAD-linked l -lactate…