Kinetics of inhibition of rat liver and kidney arginases by proline and branched-chain amino acids

1986 ◽  
Vol 870 (2) ◽  
pp. 181-184 ◽  
Author(s):  
Nelson Carvajal ◽  
Stephen D. Cederbaum
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Branched Chain Amino Acids ◽  
Liver And Kidney ◽  
Branched Chain ◽  
Kinetics Of ◽  
Kinetics Of Inhibition

Oxidation of 2-oxoisocaproate and 2-oxoisovalerate by the perfused rat heart. Interactions with fatty acid oxidation

1990 ◽  
Vol 68 (1) ◽  
pp. 260-265 ◽  
Author(s):  
Joan Letto ◽  
John T. Brosnan ◽  
Margaret E. Brosnan
Keyword(s):  
Amino Acids ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Branched Chain Amino Acids ◽  
Acid Oxidation ◽  
Perfused Heart ◽  
Acid Dehydrogenase ◽  
Liver And Kidney ◽  
Labelled Compound ◽  
Branched Chain

The interactions between fatty acid oxidation and the oxidation of the 2-oxo acids of the branched chain amino acids were studied in the isolated Langendorff-perfused heart. 2-Oxoisocaproate inhibited the oxidation of oleate, but 2-oxoisovalerate and 2-oxo-3-methylvalerate did not. This difference was not attributable to the magnitude of the flux through the branched chain 2-oxo acid dehydrogenase, which was slightly higher with 2-oxoisovalerate than with 2-oxoisocaproate. Oxidation of 2-oxoisocaproate in the perfused heart was virtually complete, since more than 80% of the isovaleryl-CoA formed from 2-oxo[1-14C]isocaproate was further metabolized to CO2, as determined by comparing 14CO2 production from 2-oxo[14C(U)]isocaproate with that from the 1-14C-labelled compound. Only twice as much 14CO2 was produced from 2-oxo[14C(U)]isovalerate as from the 1-14C-labelled compound, indicating incomplete oxidation. This was confirmed by the accumulation in the perfusion medium of substantial quantities of labelled 3-hydroxyisobutyrate (an intermediate in the pathway of valine catabolism), when hearts were perfused with 2-oxo[14C(U)]isovalerate. The failure of 2-oxoisovalerate to inhibit fatty acid oxidation, then, can be attributed to the fact that its partial metabolism in the heart produces little ATP. We have previously shown that 3-hydroxyisobutyrate is a good gluconeogenic substrate in liver and kidney, and postulate that 3-hydroxyisobutyrate serves as an interorgan metabolite such that valine can serve as a glucogenic amino acid, even when its catabolism proceeds beyond the irreversible 2-oxo acid dehydrogenase in muscle.Key words: branched chain amino acids, branched chain 2-oxoacids, perfused heart, fatty acid metabolism, 3 -hydroxyisobutyrate.

scholarly journals Developmental changes in rat liver branched-chain 2-oxo acid dehydrogenase

1982 ◽  
Vol 204 (2) ◽  
pp. 487-492 ◽  
Author(s):  
E E May ◽  
M E May ◽  
R P Aftring ◽  
M G Buse
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Maternal Diabetes ◽  
Perinatal Period ◽  
Branched Chain Amino Acids ◽  
Developmental Changes ◽  
Acid Dehydrogenase ◽  
Period 2 ◽  
Liver Homogenates ◽  
Branched Chain

Branched-chain 2-oxo acid dehydrogenase catalyses the first irreversible step in the degradation of the branched-chain amino acids leucine, isoleucine and valine. With specifically labelled 4-methyl-2-oxo[1-14C]pentanoate as substrate, the enzyme's activity was measured in rat liver homogenates. Activity (per g wet wL of liver or per mg of protein) increased most rapidly during the perinatal period (2 days before to 1 day after birth), reaching approximately adult values by the time of weaning. The apparent Vmax, of the enzyme increased with age, but its Km appeared unchanged. The data suggest that hepatic branched-chain 2-oxo acid dehydrogenase is induced or activated during the perinatal period. The enzyme's activity at birth was unaffected by maternal diabetes, or by treating the mother with pharmacological doses of corticosterone or 3,3',5-tri-iodothyronine, during the last 5 days of pregnancy.

scholarly journals Inactivation of the ilvB1 gene in Mycobacterium tuberculosis leads to branched-chain amino acid auxotrophy and attenuation of virulence in mice

Microbiology ◽  
2009 ◽  
Vol 155 (9) ◽  
pp. 2978-2987 ◽  
Author(s):  
Disha Awasthy ◽  
Sheshagiri Gaonkar ◽  
R. K. Shandil ◽  
Reena Yadav ◽  
Sowmya Bharath ◽  
...  
Keyword(s):  
Amino Acids ◽  
Mycobacterium Tuberculosis ◽  
Amino Acid ◽  
Mutant Strain ◽  
Branched Chain Amino Acids ◽  
Branched Chain Amino Acid ◽  
Branched Chain ◽  
Kinetics Of

Acetohydroxyacid synthase (AHAS) is the first enzyme in the branched-chain amino acid biosynthesis pathway in bacteria. Bioinformatics analysis revealed that the Mycobacterium tuberculosis genome contains four genes (ilvB1, ilvB2, ilvG and ilvX) coding for the large catalytic subunit of AHAS, whereas only one gene (ilvN or ilvH) coding for the smaller regulatory subunit of this enzyme was found. In order to understand the physiological role of AHAS in survival of the organism in vitro and in vivo, we inactivated the ilvB1 gene of M. tuberculosis. The mutant strain was found to be auxotrophic for all of the three branched-chain amino acids (isoleucine, leucine and valine), when grown with either C6 or C2 carbon sources, suggesting that the ilvB1 gene product is the major AHAS in M. tuberculosis. Depletion of these branched chain amino acids in the medium led to loss of viability of the ΔilvB1 strain in vitro, resulting in a 4-log reduction in colony-forming units after 10 days. Survival kinetics of the mutant strain cultured in macrophages maintained with sub-optimal concentrations of the branched-chain amino acids did not show any loss of viability, indicating either that the intracellular environment was rich in these amino acids or that the other AHAS catalytic subunits were functional under these conditions. Furthermore, the growth kinetics of the ΔilvB1 strain in mice indicated that although this mutant strain showed defective growth in vivo, it could persist in the infected mice for a long time, and therefore could be a potential vaccine candidate.

Effect of branched-chain amino acids on proteolytic enzymes gene expression in rat liver

1993 ◽  
Vol 12 ◽  
pp. 36
Author(s):  
A.L. Andreu ◽  
S. Schwartz ◽  
J. López ◽  
M.A. Arbós ◽  
M. Quiles ◽  
...  
Keyword(s):  
Gene Expression ◽  
Amino Acids ◽  
Rat Liver ◽  
Proteolytic Enzymes ◽  
Branched Chain Amino Acids ◽  
Branched Chain

Oral administration of branched-chain amino acids activates the mTOR signal in cirrhotic rat liver

2005 ◽  
Vol 33 (1) ◽  
pp. 27-32 ◽  
Author(s):  
T MATSUMURA ◽  
Y MORINAGA ◽  
S FUJITANI ◽  
K TAKEHANA ◽  
S NISHITANI ◽  
...  
Keyword(s):  
Amino Acids ◽  
Oral Administration ◽  
Rat Liver ◽  
Branched Chain Amino Acids ◽  
Branched Chain

scholarly journals Cell swelling inhibits proteolysis in perfused rat liver

1990 ◽  
Vol 272 (1) ◽  
pp. 239-242 ◽  
Author(s):  
D Häussinger ◽  
C Hallbrucker ◽  
S vom Dahl ◽  
F Lang ◽  
W Gerok
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Liver Cell ◽  
Intraperitoneal Injection ◽  
Branched Chain Amino Acids ◽  
Cell Swelling ◽  
Perfused Rat Liver ◽  
Close Relationship ◽  
Branched Chain

Exposure of isolated single-pass-perfused rat liver to hypo-osmotic media resulted in liver cell swelling and an inhibition of release of branched-chain amino acids. Similarly, cell swelling inhibited [3H]leucine release from perfused livers from rats in which liver proteins were prelabelled in vivo by intraperitoneal injection of L-[4,5-3H]leucine 16-20 h before the experiment. The effects of cell swelling on [3H]leucine release were fully reversible. [3H]Leucine release was also inhibited when cell swelling was induced by addition of glutamine (0.5-2 mM). There was a close relationship between the inhibition of [3H]leucine release and the degree of liver cell swelling, regardless of whether cell swelling was induced by hypo-osmotic perfusion or addition of glutamine. The data suggest that the known anti-proteolytic effect of glutamine is in large part due to glutamine-induced hepatocyte swelling.

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