scholarly journals The subcellular distribution of rat liver l-alanine–glyoxylate aminotransferase in relation to a pathway for glucose formation involving glyoxylate

1972 ◽  
Vol 127 (1) ◽  
pp. 155-165 ◽  
Author(s):  
E. V. Rowsell ◽  
K. Snell ◽  
J. A. Carnie ◽  
Kathleen V. Rowsell
Keyword(s):  
Rat Liver ◽  
High Speed ◽  
Mitochondrial Enzymes ◽  
Aminotransferase Activity ◽  
Ph Optimum ◽  
Cytosol Fraction ◽  
Specific Association ◽  
Differential Sedimentation ◽  
Glyoxylate Aminotransferase ◽  
Glucose Formation

1. The distribution of l-alanine–glyoxylate aminotransferase activity between subcellular fractions prepared from rat liver homogenates was investigated. The greater part of the homogenate activity (about 80%) was recovered in the `total-particles' fraction sedimented by high-speed centrifugation and the remainder in the cytosol fraction. 2. Subfractionation of the particles by differential sedimentation and on sucrose density gradients revealed a specific association between the aminotransferase and the mitochondrial enzymes glutamate dehydrogenase and rhodanese. 3. The aminotransferase activities in the cytosol and the mitochondria are due to isoenzymes. The solubilized mitochondrial enzyme has a pH optimum of 8.6, an apparent Km of 0.24mm with respect to glyoxylate and is inhibited by glyoxylate at concentrations above 5mm. The cytosol aminotransferase shows no distinct pH optimum (over the range 7.0–9.0) and has an apparent Km of 1.11mm with respect to glyoxylate; there is no evidence of inhibition by glyoxylate. 4. The mitochondrial location of the bulk of the rat liver l-alanine–glyoxylate aminotransferase activity is discussed in relation to a pathway for gluconeogenesis involving glyoxylate.

scholarly journals The subcellular distribution of rat liver serine-pyruvate aminotransferase

1982 ◽  
Vol 202 (2) ◽  
pp. 483-490 ◽  
Author(s):  
K V Rowsell ◽  
L M R Al-Naama ◽  
P Benett
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Subcellular Location ◽  
Mitochondrial Activity ◽  
Transferase Activity ◽  
Mitochondrial Enzymes ◽  
Marker Enzymes ◽  
Aminotransferase Activity ◽  
Mitochondrial Marker ◽  
Differential Sedimentation

1. The subcellular distribution of L-serine-pyruvate aminotransferase activity in rat liver was investigated. About 80% was recovered from cell-free homogenates in a ‘total-particles’ fraction and the remainder in the cytosol. 2. Subfractionation of the particles by differential sedimentation and on sucrose density gradients showed a distribution for serine-pyruvate aminotransferase activity closely matching that observed for mitochondrial marker enzymes. 3. A study of the solubilization of enzymes from combined subcellular particles by digitonin at various concentrations also indicated a common subcellular location for serine-pyruvate aminotransferase and established mitochondrial enzymes. 4. The increase in liver serine-pyruvate amino-transferase activity induced by glucagon injection was accounted for as an increased mitochondrial activity.

scholarly journals Two forms of aspartate aminotransferase in rat liver and kidney mitochondria

1968 ◽  
Vol 108 (4) ◽  
pp. 619-624 ◽  
Author(s):  
M. M. Bhargava ◽  
A. Sreenivasan
Keyword(s):  
Rat Liver ◽  
Aspartate Aminotransferase ◽  
High Speed ◽  
Rat Kidney ◽  
Liver Mitochondria ◽  
Supernatant Fraction ◽  
Rat Liver Mitochondria ◽  
Aminotransferase Activity ◽  
Kidney Mitochondria ◽  
Liver And Kidney

1. Butan-1-ol solubilizes that portion of rat liver mitochondrial aspartate aminotransferase (EC 2.6.1.1) that cannot be solubilized by ultrasonics and other treatments. 2. A difference in electrophoretic mobilities, chromatographic behaviour and solubility characteristics between the enzymes solubilized by ultrasonic treatment and by butan-1-ol was observed, suggesting the occurrence of two forms of this enzyme in rat liver mitochondria. 3. Half the aspartate aminotransferase activity of rat kidney homogenate was present in a high-speed supernatant fraction, the remainder being in the mitochondria. 4. A considerable increase in aspartate aminotransferase activity was observed when kidney mitochondrial suspensions were treated with ultrasonics or detergents. 5. All the activity after maximum activation was recoverable in the supernatant after centrifugation at 105000g for 1hr. 6. The electrophoretic mobility of the kidney mitochondrial enzyme was cathodic and that of the supernatant enzyme anodic. 7. Cortisone administration increased the activities of both mitochondrial and supernatant aspartate aminotransferases of liver, but only that of the supernatant enzyme of kidney.

scholarly journals The adaptive behaviour of isoenzyme forms of rat liver alanine amino transferases during development

1972 ◽  
Vol 128 (2) ◽  
pp. 403-413 ◽  
Author(s):  
Keith Snell ◽  
Deryck G. Walker
Keyword(s):  
Cyclic Amp ◽  
Rat Liver ◽  
In Utero ◽  
Adaptive Behaviour ◽  
Intragastric Administration ◽  
Aminotransferase Activity ◽  
Dibutyryl Cyclic Amp ◽  
Neonatal Development ◽  
Foetal Liver ◽  
Glyoxylate Aminotransferase

1. The activities of the mitochondrial and cytosol isoenzyme forms of l-alanine–glyoxylate and l-alanine–2-oxoglutarate aminotransferases were determined in rat liver during foetal and neonatal development. 2. The mitochondrial glyoxylate aminotransferase activity begins to develop in late-foetal liver, increases rapidly at birth to a peak during suckling and then decreases at weaning to the adult value. 3. The cytosol glyoxylate aminotransferase and the mitochondrial and cytosol 2-oxoglutarate aminotransferase activities first appear prenatally, increase further after birth and then rise to the adult values during weaning. 4. In foetal liver the mitochondrial glyoxylate aminotransferase and the cytosol 2-oxoglutarate aminotransferase activities are increased after injection in utero of glucagon, dibutyryl cyclic AMP (6-N,2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate) or thyroxine. The cytosol glyoxylate aminotransferase and the mitochondrial 2-oxoglutarate aminotransferase activities are increased after injection in utero of cortisol or thyroxine. 5. After birth the further normal increases in the mitochondrial and cytosol 2-oxoglutarate aminotransferase activities can be hastened by cortisol injection, whereas the increase in cytosol glyoxylate aminotransferase activity requires cortisol treatment together with the intragastric administration of casein. 6. The results are discussed with reference to the metabolic patterns and the changes in regulatory stimuli (hormonal and dietary) that occur during the period of development.

scholarly journals Purification, characterization and identification of rat liver histidine-pyruvate aminotransferase isoenzymes

1976 ◽  
Vol 155 (1) ◽  
pp. 107-115 ◽  
Author(s):  
T Noguchi ◽  
E Okuno ◽  
Y Minatogawa ◽  
R Kido
Keyword(s):  
Density Gradient ◽  
Rat Liver ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Sucrose Density Gradient ◽  
Aminotransferase Activity ◽  
Sucrose Density Gradient Centrifugation ◽  
Ph Optimum

1. Histidine-pyruvate aminotransferase (isoenzyme 1) was purified to homogeneity from the mitochondrial and supernatant fractions of rat liver, as judged by polyacrylamide-gel electrophoresis and isolectric focusing. Both enzyme preparations were remarkably similar in physical and enzymic properties. Isoenzyme 1 had pI8.0 and a pH optimum of 9.0. The enzyme was active with pyruvate as amino acceptor but not with 2-oxoglutarate, and utilized various aromatic amino acids as amino donors in the following order of activity: phenylalanine greater than tyrosine greater than histidine. Very little activity was found with tryptophan and 5-hydroxytryptophan. The apparent Km values were about 2.6mM for histidine and 2.7 mM for phenylalanine. Km values for pyruvate were about 5.2mM with phenylalanine as amino donor and 1.1mM with histidine. The aminotransferase activity of the enzyme towards phenylalanine was inhibited by the addition of histidine. The mol.wt. determined by gel filtration and sucrose-density-gradient centrifugation was approx. 70000. The mitochondrial and supernatant isoenzyme 1 activities increased approximately 25-fold and 3.2-fold respectively in rats repeatedly injected with glucagon for 2 days. 2. An additional histidine-pyruvate aminotransferase (isoenzyme 2) was partially purified from both the mitochondrial and supernatant fractions of rat liver. Nearly identical properties were observed with both preparations. Isoenzyme 2 had pI5.2 and a pH optimum of 9.3. The enzyme was specific for pyruvate and did not function with 2-oxoglutarate. The order of effectiveness of amino donors was tyrosine = phenylalanine greater than histidine greater than tryptophan greater than 5-hydroxytryptophan. The apparent Km values for histidine and phenylalanine were about 0.51 and 1.8 mM respectively. Km values for pyruvate were about 3.5mM with phenylalanine and 4.7mM with histidine as amino donors. Histidine inhibited phenylalanine aminotransferase activity of the enzyme. Gel filtration and sucrose-density-gradient centrifugation yielded a mol.wt. of approx. 90000. Neither the mitochondrial nor the supernatant isoenzyme 2 activity was elevated by glucagon injection.

scholarly journals Purification and properties of peroxisomal pyruvate (glyoxylate) aminotransferase from rat liver

1978 ◽  
Vol 175 (2) ◽  
pp. 765-768 ◽  
Author(s):  
T Noguchi ◽  
Y Takada
Keyword(s):  
Amino Acids ◽  
Kinetic Parameters ◽  
Rat Liver ◽  
Isoelectric Point ◽  
Enzyme Preparation ◽  
Ph Optimum ◽  
Purification And Properties ◽  
Amino Donor ◽  
Glyoxylate Aminotransferase ◽  
Liver Peroxisomes

Pyruvate (glyoxylate) aminotransferase from rat liver peroxisomes was highly purified and characterized. The enzyme preparation has a mol.wt. of approx. 80,000 with two identical subunits, and isoelectric point of 8.0 and a pH optimum between 8.0 and 8.5. The enzyme catalysed transamination between a number of L-amino acids and pyruvate or glyoxylate. The effective amino acceptors were pyruvate, phenylpyruvate and glyoxylate with serine, and glyoxylate and phenylpyruvate with alanine as amino donor. These properties and kinetic parameters of the enzyme are remarkably similar to those previously described for mitochondrial alanine-glyoxylate aminotransferase isoenzyme 1 from glucagon-injected rat liver [Noguchi, Okuno, Takada, Minatogawa, Okai & Kido (1978, Biochem. J. 169, 113-122].

scholarly journals Subcellular distribution of pyruvate (glyoxylate) aminotransferases in rat liver

1978 ◽  
Vol 170 (1) ◽  
pp. 173-175 ◽  
Author(s):  
T Noguchi ◽  
Y Minatogawa ◽  
Y Takada ◽  
E Okuno ◽  
R Kido
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Enzyme Activities ◽  
Particulate Fraction ◽  
Aminotransferase Activity ◽  
Liver Homogenates ◽  
Glucagon Injection ◽  
Glyoxylate Aminotransferase

The distribution of pyruvate (glyoxylate) aminotransferases in the particulate fraction of rat liver homogenates was examined by centrifugation in a sucrose density graident. Aminotransferase activities towards serine, phenylalanine and histidine with pyruvate and those towards phenylalanine and histidine with glyoxylate were nearly identically distributed. Some 50-55% of the particulate activity was localized in the peroxisomes and the remainder in the mitochondria. Most of alanine-glyoxylate aminotransferase activity was localized in the mitochondria, with some activity in the peroxisomes. Glucagon injection resulted in increases of these enzyme activities in the mitochondria, but not in the peroxisomes.

scholarly journals Biphasic effect of acute ethanol administration on rat liver tyrosine-2-oxoglutarate aminotransferase activity

1980 ◽  
Vol 186 (3) ◽  
pp. 755-761 ◽  
Author(s):  
A A B Badawy ◽  
B M Snape ◽  
M Evans
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Actinomycin D ◽  
Tyrosine Aminotransferase ◽  
Ethanol Metabolism ◽  
Ethanol Administration ◽  
Aminotransferase Activity ◽  
Biphasic Effect ◽  
Initial Decrease ◽  
Acute Ethanol

1. Acute ethanol administration causes a biphasic change in rat liver tyrosine aminotransferase activity. 2. The initial decrease is significant with a 200 mg/kg dose of ethanol, is prevented by adrenoceptor-blocking agnets and by reserpine, but not by inhibitors of ethanol metabolism, and exhibits many of the characteristics of the inhibition caused by noradrenaline. 3. The subsequent enhancement of the enzyme activity by ethanol is not associated with stabilization of the enzyme, but is sensitive to actinomycin D and cycloheximide. 4. It is suggested that the initial decrease in aminotransferase activity is caused by the release of catecholamines, whereas the subsequent enhancement may be related to the release of glucocorticoids.

Identity of alanine: glyoxylate aminotransferase with alanine: 2-oxoglutarate aminotrasferase in rat liver cytosol

Biochimie ◽  
1989 ◽  
Vol 71 (4) ◽  
pp. 471-475 ◽  
Author(s):  
Shigeru Kobayashi ◽  
Sueko Hayashi ◽  
Satoko Fujiwara ◽  
Tomoo Noguchi
Keyword(s):  
Rat Liver ◽  
Liver Cytosol ◽  
Glyoxylate Aminotransferase ◽  
Rat Liver Cytosol
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