scholarly journals Characteristics of aspartate deamination by the puring nucleotide cycle in the cytosol fraction of rat liver

1975 ◽  
Vol 150 (2) ◽  
pp. 275-283 ◽  
Author(s):  
K M Moss ◽  
J D McGivan
Keyword(s):  
Amino Acid ◽  
Rat Liver ◽  
Nucleoside Triphosphate ◽  
Amp Deaminase ◽  
Purine Nucleotide ◽  
Major Pathway ◽  
Cytosol Fraction ◽  
Purine Nucleotide Cycle

1. The component reactions of the puring nucleotide cycle were studied in cytosol extracts of rat liver. 2. AMP deaminase was strongly activated by ATP and analogues of ATP. 3. IMP was converted into ATP by a system requiring the presence of aspartate, GTP and a nucleoside triphosphate-regenerating system. 4. Under appropriate conditions, NH3 was produced from aspartate. 5. From the rates at which these reactions occur it is concluded that the purine nucleotide cycle may have sufficient activity to be a major pathway of amino acid deamination in liver.

scholarly journals Changes in the activity of rat muscle AMP deaminase in relation to the proportion of dietary protein

1974 ◽  
Vol 32 (3) ◽  
pp. 539-548 ◽  
Author(s):  
L. V. Turner ◽  
E. B. Fern
Keyword(s):  
Amino Acid ◽  
Glutamate Dehydrogenase ◽  
Dietary Protein ◽  
Metabolizable Energy ◽  
Amp Deaminase ◽  
Purine Nucleotide ◽  
Alternative Scheme ◽  
Protein Energy ◽  
Purine Nucleotide Cycle ◽  
Nutritional Studies

1. The purine nucleotide cycle has been proposed (Lowenstein, 1972) as an alternative scheme for amino acid deamination in tissues, such as skeletal muscle, having low concentrations of glutamate dehydrogenase (EC 1.4.1.2).2. Activities of AMP deaminase (EC 3.5.4.6), one of the enzymes of the cycle, have been measured in soleus, plantaris and extensor digitorum longus muscles of rats maintained for 18 d on diets providing 0, 0·035 or 0·10 net dietary protein energy (energy supplied by utilizable protein: total metabolizable energy, NDp:E), and in rats given the 0·10 NDp:E diet for 3 d after the 0 or 0·035 NDp:E regimens.3. Concentration of AMP deaminase in the different muscles from the control (0·10 NDp:E diet) rats appeared to bear an inverse relationship to the proportion of mitochondria-rich fibres (i.e. rich in glutamate dehydrogenase) in each muscle.4. Dietary protein deprivation (0 or 0·035 NDp:E) led to adaptive reductions in AMP-deaminase activity in the soleus and plantaris muscles, but in the extensor muscle the 0·035 NDp:E diet produced no change, while the 0 NDp:E diet caused an increase in activity.5. Refeeding the 0·10 NDp:E diet to the protein-deprived rats caused reductions of AMP-deaminase activity to lower levels in all three muscles, except in the instance of soleus in rats refed after the 0·035 NPp:E diet.6. In view of the different responses shown by the three muscles to the dietary treatments, the importance of specifying the particular muscles used in future nutritional studies is emphasized.7. The adaptive changes in AMP deaminase are discussed in terms of operation of the purine nucleotide cycle for amino acid deamination responding to the changes in amino acid catabolism known to be caused in muscle by these protein-deficient diets.

Ammonia and amino acid metabolism in human skeletal muscle during exercise

1992 ◽  
Vol 70 (1) ◽  
pp. 132-141 ◽  
Author(s):  
T. E. Graham ◽  
D. A. MacLean
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Steady State ◽  
Amino Acid ◽  
Human Skeletal Muscle ◽  
Branched Chain Amino Acids ◽  
Ammonia Production ◽  
Purine Nucleotide ◽  
Purine Nucleotide Cycle ◽  
Branched Chain

This review focuses on the ammonia and amino acid metabolic responses of active human skeletal muscle, with a particular emphasis on steady-state exercise. Ammonia production in skeletal muscle involves the purine nucleotide cycle and the amino acids glutamate, glutamine, and alanine and probably also includes the branched chain amino acids as well as aspartate. Ammonia production is greatest during prolonged, steady state exercise that requires 60–80% [Formula: see text] and is associated with glutamine and alanine metabolism. Under these circumstances it is unresolved whether the purine nucleotide cycle (AMP deamination) is active; if so, it must be cycling with no IMP accumulation. It is proposed that under these circumstances the ammonia is produced from slow twitch fibers by the deamination of the branched chain amino acids. The ammonia response can be suppressed by increasing the carbohydrate availability and this may be mediated by altering the availability of the branched chain amino acids. The fate of the ammonia released into the circulation is unresolved, but there is indirect evidence that a considerable portion may be excreted by the lung in expired air.Key words: glutamine, branched chain amino acids, glutamate dehydrogenase, purine nucleotide cycle.

scholarly journals Induction of amino acid transport in primary cultures of adult rat liver parenchymal cells by insulin.

1976 ◽  
Vol 251 (10) ◽  
pp. 3014-3020 ◽  
Author(s):  
R F Kletzien ◽  
M W Pariza ◽  
J E Becker ◽  
V R Potter ◽  
F R Butcher
Keyword(s):  
Amino Acid ◽  
Rat Liver ◽  
Amino Acid Transport ◽  
Primary Cultures ◽  
Acid Transport ◽  
Liver Parenchymal ◽  
Adult Rat ◽  
Parenchymal Cells

scholarly journals Amino acid sequence of the phosphorylation site of rat liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase.

1984 ◽  
Vol 259 (12) ◽  
pp. 7673-7681 ◽  
Author(s):  
K J Murray ◽  
M R El-Maghrabi ◽  
P D Kountz ◽  
T J Lukas ◽  
T R Soderling ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Rat Liver ◽  
Phosphorylation Site

scholarly journals The Purine Nucleotide Cycle

1972 ◽  
Vol 247 (1) ◽  
pp. 162-169 ◽  
Author(s):  
Keith Tornheim ◽  
John M. Lowenstein
Keyword(s):  
Purine Nucleotide ◽  
Purine Nucleotide Cycle
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