Branched-chain ketoacid dehydrogenase activity and growth of normal and mutant human fibroblasts: The effect of branched-chain amino acid concentration in culture medium

1983 ◽  
Vol 21 (9-10) ◽  
pp. 895-905 ◽  
Author(s):  
Dean J. Danner ◽  
Jean H. Priest
Keyword(s):  
Amino Acid ◽  
Dehydrogenase Activity ◽  
Acid Concentration ◽  
Culture Medium ◽  
Human Fibroblasts ◽  
Amino Acid Concentration ◽  
Branched Chain Amino Acid ◽  
Branched Chain ◽  
Ketoacid Dehydrogenase

scholarly journals Tissue-specific responses of branched-chain alpha-ketoacid dehydrogenase activity in metabolic acidosis.

1998 ◽  
Vol 9 (10) ◽  
pp. 1892-1898
Author(s):  
S R Price ◽  
X Wang ◽  
J L Bailey
Keyword(s):  
Amino Acid ◽  
Whole Body ◽  
Tissue Specific ◽  
Subunit Mrna ◽  
Branched Chain Amino Acid ◽  
Leucine Catabolism ◽  
Branched Chain ◽  
Ketoacid Dehydrogenase ◽  
Rate Limiting ◽  
Adrenalectomized Rats

In adrenalectomized rats, acidosis does not increase whole-body leucine oxidation unless a physiologic amount of glucocorticoids (dexamethasone) is also provided; an equivalent dose of dexamethasone without acidosis does not change leucine catabolism. Because the influences of acidification and glucocorticoids on branched-chain amino acid metabolism in specific organs are unknown, the function of branched-chain alpha-ketoacid dehydrogenase (BCKAD), the rate-limiting enzyme in branched-chain amino acid catabolism, in adrenalectomized rat skeletal muscle and liver, the two major tissues that degrade branched-chain amino acid was measured. In muscle of acidotic adrenalectomized rats receiving dexamethasone, basal and total BCKAD activities were increased 2.6- (P < 0.05) and 2.8-fold (P < 0.05), respectively. Neither acidosis nor dexamethasone alone increased these activities. BCKAD E1alpha subunit mRNA in muscle of acidotic rats given dexamethasone was increased 1.89-fold (P < 0.05) in parallel with the change in BCKAD activity; BCKAD E2 subunit mRNA was increased by acidosis, dexamethasone, or a combination of both stimuli. In contrast, basal BCKAD activity in liver of rats with acidosis or dexamethasone was nearly threefold lower (P < 0.05) and changes in enzyme activity reflected reduced subunit mRNA. Thus, there are reciprocal, tissue-specific changes in BCKAD function in response to acidosis.

Regional and subcellular distribution of enzymes of branched-chain amino acid metabolism in brains of normal and diabetic rats

1985 ◽  
Vol 63 (10) ◽  
pp. 1234-1238 ◽  
Author(s):  
Margaret E. Brosnan ◽  
Ann Lowry ◽  
Yasmin Wasi ◽  
Martin Lowry ◽  
John T. Brosnan
Keyword(s):  
Amino Acid ◽  
Subcellular Distribution ◽  
Brain Homogenate ◽  
Total Activity ◽  
Brain Regions ◽  
Diabetic Rats ◽  
Whole Brain ◽  
Branched Chain Amino Acid ◽  
Branched Chain ◽  
Ketoacid Dehydrogenase

Branched-chain-amino-acid:α-ketoglutarate transaminase and branched-chain α-ketoacid dehydrogenase have been assayed in brains of control and of streptozotocin-induced diabetic rats. Enzyme activities were measured in five distinct regions of the brain: cerebellum, pons + medulla, midbrain, thalamus + hypothalamus, and telencephalon. Subcellular distribution of these enzymes in whole brain was assessed by fractionating brain homogenate into cytoplasm, free mitochondria, and synaptosomes. The following enzymes were used as markers: lactate dehydrogenase for cytoplasm, glutamate dehydrogenase for mitochondria, and glutamate decarboxylase for synaptosomes. The activity of the branched-chain amino acid transaminase in all brain regions was considerably higher than that of the branched-chain α-ketoacid dehydrogenase. While the highest activity of the transaminase occurred in brain-stem regions, the highest activity of the dehydrogenase was present in cerebellum and telencephalon. Diabetes did not affect the activity of the transaminase, but it caused a decrease in the total activity of the dehydrogenase in midbrain and in thalamus + hypothalamus. The transaminase was localized in the cytoplasmic fraction of whole brain, while the dehydrogenase was enriched in the free mitochondria.

Effect of alpha-ketoacid dehydrogenase phosphorylation on branched-chain amino acid metabolism in muscle

1991 ◽  
Vol 261 (5) ◽  
pp. E628-E634 ◽  
Author(s):  
D. A. Hood ◽  
R. L. Terjung
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Energy Demand ◽  
Mitochondrial Content ◽  
Branched Chain Amino Acid ◽  
Branched Chain ◽  
Ketoacid Dehydrogenase ◽  
Fold Activation

The regulation of leucine and valine metabolism was evaluated in skeletal muscle of perfused rat hindlimb. Control of the branched-chain alpha-ketoacid dehydrogenase (BCKADH) via phosphorylation was removed with 0.4 mM alpha-chloroisocaproate (CIC). CIC activated the BCKADH complex 13- to 26-fold and led to increased rates of leucine and valine uptake into muscle, transamination to the corresponding alpha-ketoacid, and leucine (3- to 4-fold) and valine (6-fold) decarboxylation but led to decreased rates of alpha-ketoacid efflux from muscle. Although the increased rates of branched-chain amino acid (BCAA) decarboxylation were extensive, they were far below the extent of BCKADH activation as measured in vitro, suggesting that factors other than BCKADH activation become dominant in controlling the flux through alpha-ketoacid decarboxylation in skeletal muscle in situ. When the BCKADH capacity of muscle was increased 70–90% by a training-induced increase in mitochondrial content, the same 13- to 26-fold activation of the complex by CIC led to a rate of BCAA decarboxylation, which was only marginally greater (10–20%; P less than 0.05) than that of normal muscle. In addition, increasing the energy demand via muscle contractions led to a significant increase in leucine decarboxylation in the presence of complete activation of BCKADH by dephosphorylation. Thus BCKADH phosphorylation-dephosphorylation plays an important though not exclusive role in modulating the rates of BCAA metabolism in skeletal muscle. Differences in valine and leucine metabolism were apparent as valine catabolism bolstered citric acid cycle contents by increasing malate in red muscle with high mitochondrial content.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Plasma branched-chain and aromatic amino acid concentration after ingestion of an urban or rural diet in rural Mexican women

BMC Obesity ◽  
2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Adriana M López ◽  
Lilia G Noriega ◽  
Margarita Diaz ◽  
Nimbe Torres ◽  
Armando R Tovar
Keyword(s):  
Amino Acid ◽  
Acid Concentration ◽  
Aromatic Amino Acid ◽  
Amino Acid Concentration ◽  
Mexican Women ◽  
Branched Chain
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