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 The subcellular distribution of alanine-glyoxylate aminotransferase and serine-pyruvate aminotransferase in dog liver

1979 ◽  
Vol 182 (3) ◽  
pp. 877-879 ◽  
Author(s):  
E Okuno ◽  
Y Minatogawa ◽  
J Nakanishi ◽  
M Nakamura ◽  
N Kamoda ◽  
...  
Keyword(s):  
Density Gradient ◽  
Subcellular Distribution ◽  
Enzyme Activities ◽  
Sucrose Density Gradient ◽  
Particulate Fraction ◽  
Glyoxylate Aminotransferase ◽  
Dog Liver

The subcellular distributions of alanine-glyoxylate aminotransferase and serine-pyruvate aminotransferase in the particulate fraction of dog liver were examined by centrifugation in a sucrose density gradient. Most of both enzyme activities in the particulate fraction were localized in the mitochondria, but not in the peroxisomes.

scholarly journals Subcellular distribution of rat liver L-alanine-glyoxylate aminotransferase

1970 ◽  
Vol 119 (5) ◽  
pp. 64P-64P
Author(s):  
K Snell ◽  
E V Rowsell ◽  
J A Carnie
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Glyoxylate Aminotransferase

scholarly journals Subcellular Distribution of Histone-Degrading Enzyme Activities from Rat Liver

1976 ◽  
Vol 62 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Peter C. HEINRICH ◽  
Gerhard RAYDT ◽  
Bernd PUSCHENDORF ◽  
Mirna JUSIC
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Enzyme Activities ◽  
Degrading Enzyme

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 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 Hepatic Golgi fractions resolved into membrane and content subfractions.

1982 ◽  
Vol 92 (3) ◽  
pp. 822-832 ◽  
Author(s):  
K E Howell ◽  
G E Palade
Keyword(s):  
Electron Microscopy ◽  
Rat Liver ◽  
Enzyme Activities ◽  
Degree Of Contamination ◽  
Golgi Membranes ◽  
Membrane Enzyme ◽  
Biochemical Assays ◽  
The Reformation ◽  
Liver Homogenates

Golgi fractions isolated from rat liver homogenates have been resolved into membrane and content subfractions by treatment with 100 mM Na2CO3 pH 11.3. This procedure permitted extensive extraction of content proteins and lipoproteins, presumably because it caused an alteration of Golgi membranes that minimized the reformation of closed vesicles. The type and degree of contamination of the fractions was assessed by electron microscopy and biochemical assays. The membrane subfraction retained 15% of content proteins and lipids, and these could not be removed by various washing procedures. The content subfraction was contaminated by both membrane fragments and vesicles and accounted for 5 to 10% of the membrane enzyme activities of the original Golgi fraction. The lipid compositions of the subfractions was determined, and the phospholipids of both membrane and content were found to be uniformly labeled with [33P]phosphate administered in vivo.

scholarly journals Increased liver l-serine–pyruvate aminotransferase activity under gluconeogenic conditions (Short Communication)

1973 ◽  
Vol 134 (1) ◽  
pp. 349-351 ◽  
Author(s):  
Edward V. Rowsell ◽  
Ali H. Al-Tai ◽  
John A. Carnie ◽  
Kathleen V. Rowsell
Keyword(s):  
Rat Liver ◽  
Short Communication ◽  
Neonatal Period ◽  
Normal Adult ◽  
Aminotransferase Activity ◽  
Serine Dehydratase ◽  
Glucagon Injection ◽  
Alloxan Injection

Rat liver l-serine–pyruvate aminotransferase activity exceeds markedly the normal adult value (a) in the neonatal period, (b) after glucagon injection and (c) after alloxan injection, observations that reinforce the suggestion from comparative findings that the aminotransferase has a role in gluconeogenesis. Some findings, however, argue in favour of l-serine dehydratase as the enzyme of gluconeogenesis from l-serine.

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.

O n the Mechanism of Inactivation and ATP-Dependent Reactivation of Rat Liver Tyrosine Aminotransferase

1977 ◽  
Vol 32 (9-10) ◽  
pp. 777-780 ◽  
Author(s):  
Hans-Heinrich Hamm ◽  
Werner Seubert
Keyword(s):  
Rat Liver ◽  
Tyrosine Aminotransferase ◽  
Particulate Fraction ◽  
Kidney Cortex ◽  
Aminotransferase Activity ◽  
Liver And Kidney ◽  
Membrane Bound ◽  
Nucleotide Specificity

Abstract The mechanism of in vitro inactivation and ATP-dependent rapid reactivation of rat liver tyrosine aminotransferase by a membrane-bound system from rat liver and kidney cortex and the nucleotide specificity of this process was investigated using partially purified tyrosine amino­ transferase as a substrate. Adenosine 5′-triphosphate (ATP) could be replaced by guanosine 5′-tri-phosphate (GTP), whereas inosine 5′-triphosphate (ITP) was less effective. During reactivation [γ-32P]A T P was incorporated into the enzyme and not excorporated by incubation of the labeled enzyme with excess non-radioative ATP. Inactivation of labeled tyrosine aminotransferase by a particulate fraction led to a decrease protein-bound radioactivity concomitant with an increase of [32P] orthophosphate. This points to a phosphorylation and dephosphorylation mechanism in the regulation of tyrosine aminotransferase activity.

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