Assessment of effects of amino acids and branched chain keto acids on leucine oxidation in human lymphocytes

1988 ◽  
Vol 48 (6) ◽  
pp. 531-536 ◽  
Author(s):  
G. Schafer ◽  
P. Schauder
Keyword(s):  
Amino Acids ◽  
Human Lymphocytes ◽  
Leucine Oxidation ◽  
Keto Acids ◽  
Branched Chain ◽  
Branched Chain Keto Acids

Influence of branched-chain amino acids and branched-chain keto acids on protein synthesis in isolated hepatocytes

Hepatology ◽  
1987 ◽  
Vol 7 (2) ◽  
pp. 324-329 ◽  
Author(s):  
Wolfgang Base ◽  
Carl Barsigian ◽  
Alisa Schaeffer ◽  
Ellen Shaw ◽  
Jose Martinez ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Isolated Hepatocytes ◽  
Branched Chain Amino Acids ◽  
Keto Acids ◽  
Branched Chain ◽  
Branched Chain Keto Acids

Transamination of branched-chain keto acids by isolated perfused rat kidney.

1978 ◽  
Vol 235 (1) ◽  
pp. E47
Author(s):  
W E Mitch ◽  
W Chan
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Branched Chain Amino Acid ◽  
Keto Acids ◽  
Perfused Rat Kidney ◽  
Branched Chain ◽  
Branched Chain Keto Acids ◽  
Isolated Rat

Isolated rat kidney perfused without substrate released serine, glycine, and taurine, and substantially smaller amounts of other amino acids. When branched-chain keto acids were added, the corresponding amino acids were released at rates amounting to 15-25% of keto acid disappearance. Perfusion with 2 mM alpha-keto-isovalerate or alpha-keto-beta-methylvalerate caused an increased glucose release amounting to 18-23% of keto acid disappearance. The activity of branched-chain amino acid transferase (BATase) was significantly stimulated by perfusion with the analogue of leucine, but not by perfusion with alpha-ketoglutarate, the analogues of valine or isoleucine, or with leucine itself. These findings document that the kidney converts branched-chain keto acids in part to the corresponding amino acids and suggest that the keto analogue of leucine may be involved in the control of renal BATase activity, thereby indirectly regulating the metabolism of branched-chain amino acids.

scholarly journals Branched-Chain Amino Acids and Branched-Chain Keto Acids in Hyperammonemic States: Metabolism and as Supplements

Metabolites ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 324 ◽  
Author(s):  
Milan Holeček
Keyword(s):  
Amino Acids ◽  
Branched Chain Amino Acids ◽  
Muscle Performance ◽  
Strenuous Exercise ◽  
Protein Balance ◽  
Keto Acids ◽  
Amino Acid Imbalance ◽  
Branched Chain ◽  
Cycle Disorders ◽  
Branched Chain Keto Acids

In hyperammonemic states, such as liver cirrhosis, urea cycle disorders, and strenuous exercise, the catabolism of branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) is activated and BCAA concentrations decrease. In these conditions, BCAAs are recommended to improve mental functions, protein balance, and muscle performance. However, clinical trials have not demonstrated significant benefits of BCAA-containing supplements. It is hypothesized that, under hyperammonemic conditions, enhanced glutamine availability and decreased BCAA levels facilitate the amination of branched-chain keto acids (BCKAs; α-ketoisocaproate, α-keto-β-methylvalerate, and α-ketoisovalerate) to the corresponding BCAAs, and that BCKA supplementation may offer advantages over BCAAs. Studies examining the effects of ketoanalogues of amino acids have provided proof that subjects with hyperammonemia can effectively synthesize BCAAs from BCKAs. Unfortunately, the benefits of BCKA administration have not been clearly confirmed. The shortcoming of most reports is the use of mixtures intended for patients with renal insufficiency, which might be detrimental for patients with liver injury. It is concluded that (i) BCKA administration may decrease ammonia production, attenuate cataplerosis, correct amino acid imbalance, and improve protein balance and (ii) studies specifically investigating the effects of BCKA, without the interference of other ketoanalogues, are needed to complete the information essential for decisions regarding their suitability in hyperammonemic conditions.

Abstract MP125: Branched-chain Keto Acids, Not Branched-chain Amino Acids, Impairs Cardiac Insulin Sensitivity by Disrupting Insulin Signaling in the Mitochondria

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Qutuba Karwi ◽  
Golam Mezbah Uddin ◽  
Cory S Wagg ◽  
Gary D Lopaschuk
Keyword(s):  
Insulin Resistance ◽  
Amino Acids ◽  
Insulin Sensitivity ◽  
Glucose Oxidation ◽  
Branched Chain Amino Acids ◽  
Mitochondrial Translocation ◽  
Oxidation Rates ◽  
Keto Acids ◽  
Branched Chain ◽  
Branched Chain Keto Acids

Alterations in branched-chain amino acids (BCAA) oxidation have been linked to the development of cardiac insulin resistance and its negative impact on cardiac function. However, it is not clear if these detrimental effects are due to the accumulation of BCAAs or branched-chain keto acids (BCKAs). It is also unknown how impaired BCAAs oxidation mediates cardiac insulin resistance. To examine this, we specifically deleted mitochondrial branched-chain aminotransferase (BCATm) in the heart to selectively increase in BCAAs and decrease in BCKAs in the heart. BCATm -/- mice had normal cardiac function compared to their wildtype littermates (WT Cre+/+ ). However, there was a significant increase in insulin-stimulated cardiac glucose oxidation rates in BCATm -/- mice, independent of any changes in glucose uptake or glycolytic rates. This enhancement in cardiac insulin sensitivity was associated with an increase in the phosphorylation of Akt and activation of pyruvate dehydrogenase (PDH), the rate-limiting enzyme of glucose oxidation. To determine the impact of reversing these events, we examined the effects of increasing cardiac BCKAs on cardiac insulin sensitivity. We perfused isolated working mice hearts with high levels of BCKAs (α;-keto-isocaproate 80 μM, α;-keto-β;-methylvalorate 100μM, α;-keto-isovalorate 70 μM), levels that can be seen during diabetes and obesity. The BCKAs completely blunted insulin-stimulated glucose oxidation rates. We also found that BCKAs abolished insulin-stimulated mitochondrial translocation of Akt, an effect which was associated with PDH deactivation. We conclude that the accumulation of BCKAs, and not BCAAs, is a major contributor to cardiac insulin resistance via abrogating mitochondrial translocation of Akt.

scholarly journals CodY-Regulated Aminotransferases AraT and BcaT Play a Major Role in the Growth of Lactococcus lactis in Milk by Regulating the Intracellular Pool of Amino Acids

2003 ◽  
Vol 69 (6) ◽  
pp. 3061-3068 ◽  
Author(s):  
Emilie Chambellon ◽  
Mireille Yvon
Keyword(s):  
Amino Acids ◽  
Growth Inhibition ◽  
Lactococcus Lactis ◽  
Double Mutant ◽  
Wild Type Strain ◽  
Aromatic Amino Acids ◽  
Nitrogen Sources ◽  
Nutritional Factors ◽  
Keto Acids ◽  
Branched Chain

ABSTRACT Aminotransferases, which catalyze the last step of biosynthesis of most amino acids and the first step of their catabolism, may be involved in the growth of Lactococcus lactis in milk. Previously, we isolated two aminotransferases from L. lactis, AraT and BcaT, which are responsible for the transamination of aromatic amino acids, branched-chain amino acids, and methionine. In this study, we demonstrated that double inactivation of AraT and BcaT strongly reduced the growth of L. lactis in milk. Supplementation of milk with amino acids and keto acids that are substrates of both aminotransferases did not improve the growth of the double mutant. On the contrary, supplementation of milk with isoleucine or a dipeptide containing isoleucine almost totally inhibited the growth of the double mutant, while it did not affect or only slightly affected the growth of the wild-type strain. These results suggest that AraT and BcaT play a major role in the growth of L. lactis in milk by degrading the intracellular excess isoleucine, which is responsible for the growth inhibition. The growth inhibition by isoleucine is likely to be due to CodY repression of the proteolytic system, which is necessary for maximal growth of L. lactis in milk, since the growth of the CodY mutant was not affected by addition of isoleucine to milk. Moreover, we demonstrated that AraT and BcaT are part of the CodY regulon and therefore are regulated by nutritional factors, such as the carbohydrate and nitrogen sources.

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