Leucine and isoleucine activate skeletal muscle branched-chain alpha-keto acid dehydrogenase in vivo

1986 ◽  
Vol 250 (5) ◽  
pp. E599-E604 ◽  
Author(s):  
R. P. Aftring ◽  
K. P. Block ◽  
M. G. Buse
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Total Activity ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Muscle Enzyme ◽  
Phosphatase Inhibitors ◽  
Acid Dehydrogenase ◽  
Branched Chain

The response of rat skeletal muscle branched-chain alpha-keto acid dehydrogenase to administration of branched-chain amino acids in vivo was determined using a soluble preparation of the enzyme. After detergent extraction of the complex in the presence of kinase and phosphatase inhibitors, initial in vivo activity was typically 1 nmol X min-1 X g muscle-1, with 0.1 mM alpha-[1-14C]ketoisocaproate as substrate. Total activity of the dephosphorylated complex, measured after preincubation with 15 mM Mg2+, typically reached a maximum of 29 nmol X min-1 X g-1. Thus in overnight-fasted rats the complex was 2-3% active. Initial activity increased three- to fivefold after leucine or isoleucine (at higher concentrations) but not valine administration in vivo. After intravenous leucine injection (0.25 mmol/kg) initial muscle enzyme activity increased rapidly and subsequently decreased, paralleling plasma leucine concentrations, while plasma valine and isoleucine decreased. In conclusion, muscle branched-chain alpha-keto acid dehydrogenase complex is rapidly activated when circulating leucine is increased to concentrations that may occur after meals. During hyperleucinemia accelerated valine and isoleucine degradation by muscle may account for the observed "antagonism" among the branched-chain amino acids.

scholarly journals Enzymic determination of branched-chain amino acids and 2-oxoacids in rat tissues. Transfer of 2-oxoacids from skeletal muscle to liver in vivo

1980 ◽  
Vol 188 (3) ◽  
pp. 705-713 ◽  
Author(s):  
G Livesey ◽  
P Lund
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Bacillus Subtilis ◽  
Branched Chain Amino Acids ◽  
Rat Tissues ◽  
Arterial Blood ◽  
Branched Chain ◽  
Arteriovenous Difference

1. A procedure is described for the purification of leucine dehydrogenase (EC 1.4.1.9) from Bacillus subtilis. 2. The preparation is suitable for the quantitative assay of branched-chain amino acids and their 2-oxoacid analogues. 3. The content of total branched-chain 2-oxoacids in freeze-clamped liver, kidney, heart or mammary gland of fed rats is less than 5 nmol/g fresh wt. Higher amounts are present in skeletal muscle and arterial blood (25 +/- 4 nmol per g fresh wt., and 33 +/- 6 nmol per ml respectively; means +/- S.D. of 3 and 11 animals respectively). The values are not significantly affected by starvation for 24 h. 4. Arteriovenous difference measurements show that considerable amounts of branched-chain 2-oxoacids are released by skeletal muscle into the circulation and similar amounts are removed by the liver (about 1 mmol/24 h in a 400 g rat).

Effects of diabetes and starvation on skeletal muscle branched-chain alpha-keto acid dehydrogenase activity

1988 ◽  
Vol 254 (3) ◽  
pp. E292-E300 ◽  
Author(s):  
R. P. Aftring ◽  
W. J. Miller ◽  
M. G. Buse
Keyword(s):  
Skeletal Muscle ◽  
Insulin Treatment ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Acid Dehydrogenase ◽  
Hindlimb Muscles ◽  
Activation Response ◽  
Branched Chain ◽  
Persistent Elevation ◽  
Significant Activation

The activation state of branched-chain alpha-keto acid dehydrogenase (BCDH) was studied in rat hindlimb muscles during starvation and insulinopenic diabetes, conditions in which circulating branched-chain amino acids (BCAA) are increased and their oxidation is accelerated. Muscle BCDH is predominantly inactive (phosphorylated) in postabsorptive rats but is activated by increased circulating leucine. Diabetes (streptozotocin-induced and spontaneous BB/W) increased circulating BCAA four- to fivefold and BCDH activity approximately threefold. Insulin treatment caused near normalization of circulating BCAA without correcting BCDH activity. Adrenalectomy of diabetics decreased (without normalizing) circulating BCAA and BCDH activation. Starvation caused mild, progressive increases in circulating BCAA and significant activation of BCDH only after 4 days. Leucine infusion activated BCDH in muscle but the activation by leucine was markedly blunted by diabetes. In isolated perfused hindlimbs (control and diabetic) insulin did not affect BCDH significantly; perfusion with leucine activated BCDH, and this response appeared blunted in diabetics. Activation of muscle BCDH may contribute to increased BCAA catabolism in diabetes; the blunted activation response to hyperleucinemia may spare BCAA and contribute to their persistent elevation in plasma.

scholarly journals Interactions among the branched-chain amino acids and their effects on methionine utilization in growing pigs: effects on plasma amino– and keto–acid concentrations and branched-chain keto-acid dehydrogenase activity

2000 ◽  
Vol 83 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Stefan Langer ◽  
Peter W. D. Scislowski ◽  
David S. Brown ◽  
Peter Dewey ◽  
Malcolm F. Fuller
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Concentrations ◽  
Biceps Femoris ◽  
Branched Chain Amino Acids ◽  
Growing Pigs ◽  
Keto Acid ◽  
Blood Samples ◽  
Acid Dehydrogenase ◽  
Branched Chain

The present experiment was designed to elucidate the mechanism of the methionine-sparing effect of excess branched-chain amino acids (BCAA) reported in the previous paper (Langer & Fuller, 2000). Twelve growing gilts (30–35 kg) were prepared with arterial catheters. After recovery, they received for 7 d a semipurified diet with a balanced amino acid pattern. On the 7th day blood samples were taken before (16 h postabsorptive) and after the morning meal (4 h postprandial). The animals were then divided into three groups and received for a further 7 d a methionine-limiting diet (80 % of requirement) (1) without any amino acid excess; (2) with excess leucine (50 % over requirement); or (3) with excesses of all three BCAA (leucine, isoleucine, valine, each 50 % over the requirement). On the 7th day blood samples were taken as in the first period, after which the animals were killed and liver and muscle samples taken. Plasma amino acid and branched-chain keto acid (BCKA) concentrations in the blood and branched-chain keto-acid dehydrogenase (BCKDH; EC 1.2.4.4) activity in liver and muscle homogenates were determined. Compared with those on the balanced diet, pigs fed on methionine-limiting diets had significantly lower (P < 0·05) plasma methionine concentrations in the postprandial but not in the postabsorptive state. There was no effect of either leucine or a mixture of all three BCAA fed in excess on plasma methionine concentrations. Excess dietary leucine reduced (P < 0·05) the plasma concentrations of isoleucine and valine in both the postprandial and postabsorptive states. Plasma concentrations of the BCKA reflected the changes in the corresponding amino acids. Basal BCKDH activity in the liver and total BCKDH activity in the biceps femoris muscle were significantly (P < 0·05) increased by excesses of leucine or all BCAA.

Activation of branched-chain alpha-keto acid dehydrogenase complex by exercise: effect of high-fat diet intake

1990 ◽  
Vol 68 (1) ◽  
pp. 161-165 ◽  
Author(s):  
Y. Shimomura ◽  
T. Suzuki ◽  
S. Saitoh ◽  
Y. Tasaki ◽  
R. A. Harris ◽  
...  
Keyword(s):  
Amino Acids ◽  
Branched Chain Amino Acids ◽  
Enzyme Complex ◽  
Keto Acid ◽  
High Fat ◽  
Acid Dehydrogenase ◽  
Activity State ◽  
Branched Chain ◽  
Acid Dehydrogenase Complex ◽  
Dehydrogenase Complex

The effect of exercise on the activity of branched-chain alpha-keto acid dehydrogenase complex in liver and muscle was studied in rats fed a high-fat (FAT) or a high-carbohydrate (CHO) diet. Both diet groups of rats were offered isoenergetic diets by a meal-feeding method and were trained by treadmill running. On the final day of the experiment, half of the rats in each diet group were exercised by 2 h of running just before they were killed. The activity state of the enzyme complex was elevated maximally by exercise in liver of rats fed the FAT diet but not in liver of rats fed the CHO diet, suggesting that catabolism of branched-chain amino acids in rat liver during exercise was enhanced by the FAT diet. The activity state of the enzyme complex in muscle was enhanced by exercise in both groups of rats, but a significant difference was not observed between the groups. The concentration of branched-chain amino acids was elevated in liver and muscle by exercise in both groups of rats, but the elevated levels in liver were lower in rats fed the FAT diet than in those fed the CHO diet. Serum branched-chain amino acid concentrations were significantly lower in rested rats fed the FAT diet than in those fed the CHO diet, and the leucine and isoleucine concentrations in the former were elevated by exercise, but the serum concentrations in the latter were not significantly affected by exercise. ATP and ADP concentrations in muscle were not significantly affected by either diet or exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The adaptation in musle oxidation of leucine to dietary protein and energy intake

1974 ◽  
Vol 31 (3) ◽  
pp. 333-342 ◽  
Author(s):  
R. D. Sketcher ◽  
E. B. Fern ◽  
W. P. T. James
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Dehydrogenase Activity ◽  
Liver Enzyme ◽  
Branched Chain Amino Acids ◽  
Metabolizable Energy ◽  
Muscle Enzyme ◽  
Oxidation Activity ◽  
Branched Chain

1. Female hooded rats (65g) were maintained on a high-protein (HP) or low-protein (LP) diet for 2 weeks (ratio, energy supplied by utilizable protein: total metabolizable energy 10 and 3.5 respectively) and the oxidation of both L- and DL-[1-14C]leucine in vivo was measured in the fed and fasted animal.2. Oxidation of leucine in vivo was reduced in the animals given the LP diet. Fasting caused an increase in the oxidation of the branched-chain amino acids.3. Leucine-α-oxoglutarate transaminase (EC 2.6.1.6) and α-ketoisocaproic acid dehydrogenase were measured in both liver and gastrocnemius muscle from rats fed on the HP or LP diet. Enzymes were also assayed after a 48 h fast in a group of animals previously maintained on the HP diet.4. The LP diet led to a fall in muscle dehydrogenase activity without any alterations in liver enzyme activity. Fasting also reduced muscle dehydrogenase activity but increased liver dehydrogenase activity.5. The presence of a dehydrogenase in muscle and its ability to adapt to dietary stress at a time when the liver enzyme is unaffected suggests that muscle is the most important site for control of leucine oxidation.6. Transaminase activity in muscle rose in the LP and fasted animals but the activity in liver was unchanged.7. Oxidation, incorporation into protein of [U-14C]leucine and the pool sizes of free leucine in plasma and in the extensor digitorum longus muscles were measured. The rats were maintained under the feeding conditions described above. The ability of incubated muscles to incorporate [14C]leucine into protein in both the fasted animals and those fed on the LP diet was reduced. Oxidation of leucine in muscle was reduced in protein deficiency but there was little change in the evolution of 14CO2 from [U-14C]leucine on fasting.8. The increase in pool size of free leucine in fasted animals is probably important in determining its rate of oxidation in muscle, as 14CO2 production was maintained despite falling activities of the dehydrogenase enzyme activity. The muscle enzyme accounted for 90% of the calculated body capacity for oxidation; activity in liver is insufficient to deal with normal rates of oxidation. Muscle enzyme is normally in excess of that required for the oxidation of branched-chain amino acids.

Branched chain amino Acids as in vitro and in vivo Anti-Oxidation Compounds

2021 ◽  
pp. 3899-3904
Author(s):  
Moath Alqaraleh ◽  
Violet Kasabri ◽  
Ibrahim Al-Majali ◽  
Nihad Al-Othman ◽  
Nihad Al-Othman ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Amino Acids ◽  
Branched Chain Amino Acids ◽  
Raw 264.7 ◽  
Raw 264.7 Cell ◽  
Branched Chain ◽  
Raw 264.7 Cell Line

Background and aims: Branched chain amino acids (BCAAs) can be tightly connected to metabolism syndrome (MetS) which can be counted as a metabolic indicator in the case of insulin resistance (IR). The aim of this study was to assess the potential role of these acids under oxidative stress. Material and Methods: the in vitro antioxidant activity of BCAAs was assessed using free radical 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging assays. For further check, a qRT-PCR technique was madefor detection the extent of alterations in gene expression of antioxidative enzymes (catalase and glutathione peroxidase (Gpx)) in lipopolysaccharides (LPS(-induced macrophages RAW 264.7 cell line. Additionally, BCAAs antioxidant activity was evaluated based on plasma H2O2 levels and xanthine oxidase (XO) activity in prooxidative LPS-treated mice. Results: Different concentrations of BCAAs affected on DPPH radical scavenging activity but to lesser extent than the ascorbic acid. Besides, BCAAs obviously upregulated the gene expression levels of catalases and Gpx in LPS-modulated macrophage RAW 264.7 cell line. In vivo BCAAs significantly minimized the level of plasma H2O2 as well as the activity of XO activity under oxidative stress. Conclusion: our current findings suggest that BCAAs supplementation may potentially serve as a therapeutic target for treatment of oxidative stress occurs with atherosclerosis, IR-diabetes, MetS and tumorigenesis.

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