• Parasites, Hosts and Diseases
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• v.21 no.1
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• pp.49-57
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• 1983

The distribution and Properties of branched chain amino acid aminotransferase (EC 2.6. 1.42) was investigated in adult Fasciola hepatica. Fascicla hepatica was fractionated by differential centrifugation into nuclear, mitochondrial and cytosolic fractions. The activity of branched chain amino acid aminotransferase was measured by the method of Ichihara and Koyama (1966) . Isozyme patterns of this enzyule was also examined by DEAE-cellulose column chromatography. The results obtained were as follows; 1. The activity in homogenate was found to be 12.69 units/g wet tissue. The activity of this enzyme was relatively high compared with those in rat tissues. 2. The distribution of branched chain amino acid aminotransferase in the subcellular organelles showed that 87.8% of the activity was in cytosolic, 10.9% in mitochondrial and 1.3% was in nuclear fraction. 3. Cytosolic fraction of Fasciola hepatica contained Enzyme I, but not Enzyme II and III, of branched chain amino acid aminotransferase. Ensyme I was eluted by 50mM phosphate buffier from DEAE-cellulose column and catalyzed the transamination of all three branched chain amino acids. 4. The Enzyme I was purified about 22-folds increase in specific activity after chromatography on DEAE-cellulose. 5. The best substrate among three amino acids (leucine, isoleucine and valise) was L-isoleucine. 6. The optimal temperature of Enzyme I was $45^{\circ}C$ and the optimal pH was 8.2. 7. The Km value for leucine of Enzyme I was 4.17 mM. 8. The Km values for a-ketoglutarate and pyridoxal phosphate of Enzyme I were 0.41mM and $4.76{\times}10^{-3}{\;}mM$, respectively.

• Journal of Microbiology and Biotechnology
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• v.21 no.10
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• pp.1049-1052
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• 2011

In this study, we demonstrated the asymmetric synthesis of L-tert-leucine from trimethylpyruvate using branched-chain aminotransferase (BCAT) from Escherichia coli in the presence of L-glutamate as an amino donor. Since BCAT was severely inhibited by 2-ketoglutarate, in order to overcome this here, we developed a BCAT/aspartate aminotransferase (AspAT) and BCAT/AspAT/pyruvate decarboxylase (PDC) coupling reaction. In the BCAT/AspAT/PDC coupling reaction, 89.2 mM L-tert-leucine (ee>99%) was asymmetrically synthesized from 100 mM trimethylpyruvate.

• Korean Journal of Clinical Laboratory Science
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• v.37 no.2
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• pp.78-83
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• 2005

The optimum conditions of Cordyceps militaris mycelial growth, purification and characteristics of branched-chain amino acid aminotransferase [BCAT(EC 2.6.1.42)] in this mycelium were studied. Optimum pH, temperature and medium of culture of mycelia were 5.5, $22.5^{\circ}C$ and Hamada medium (HM), respectively. BCAT in homogenate of this mycelia was precipitated by 20-40% saturated solution of ammonium sulfate and then purified by DEAE (diethylaminoethyl)-Sephadex A-50 column chromatography with linear concentration gradient and Sephadex G-200 gel filtration. A single band of purified enzyme was detected on SDS-PAGE (sodium dodecylsulfate-polyacrylamide gel electrophoresis). Optimum pH and temperature of BCAT were found to be 7.8 and $29^{\circ}C$, respectively. It showed activity toward L-leucine, L-isoleucine and L-valine as a substrate. The Km values of this enzyme for L-leucine were determined to be 5.88 mM for L-leucine.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.695-703
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• 1999

We have studied the stereospecificities of various pyridoxal 5'-phosphate (PLP) dependent enzymes for the hydrogen transfer between the C-4' of a bound coenzyme and the C-2 of a substrate in the transamination catalyzed by the enzymes. Stereospecificities reflect the structures of enzyme active-sites, in particular the geometrical relationship between the coenzyme-substrate Schiff base and the active site base participating in an $\alpha$-hydrogen abstraction. The PLP enzymes studied so far catalyze only a si-face specific (pro-S) hydrogen transfer. This stereochemical finding suggests that the PLP enzymes have the same topological active-site structures, and that the PLP enzymes have evolved divergently from a common ancestral protein. However, we found that o-amino acid aminotransferase, branched chain L-amino acid aminotransferase, and 4-amino-4-deoxychorismate lyase, which have significant sequence homology with one another, catalyze a re-face specific (pro-R) hydrogen transfer. We also showed that PLP-dependent amino acid racemases, which have no sequence homology with any aminotransferases, catalyze a non-stereospecific hydrogen transfer: the hydrogen transfer occurs on both faces of the planar intermediate. Crystallographical studies have shown that the catalytic base is situated on the re-face of the C-4' of the bound coenzyme in o-amino acid aminotransferase and branched chain L-amino acid aminotransferase, whereas the catalytic base is situated on the si-face in other aminotransferases (such as L-aspartate aminotransferase) catalyzing the si-face hydrogen transfer. Thus, we have clarified the stereospecificities of PLP enzymes in relation with the primary structures and three-dimensional structures of the enzymes. The characteristic stereospecificities of these enzymes for the hydrogen transfer suggest the convergent evolution of PLP enzymes.

• Korean Journal of Exercise Nutrition
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• v.24 no.4
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• pp.28-33
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• 2020

[Purpose] This study aimed to investigate the effects of branched-chain amino acid (BCAA) supplement on delayed onset muscle soreness (DOMS) by analyzing the maximum muscle strength and indicators of muscle damage. [Methods] Twelve men with majors in physical education were assigned to the BCAA group and placebo group in a double-blinded design, and repeated measurements were conducted. DOMS was induced with an isokinetic exercise. Following BCAA administration, the changes in the knee extension peak torque, flexion peak torque, aspartate aminotransferase (AST), creatine kinase (CK), and lactate dehydrogenase (LDH) concentrations were analyzed. The maximum knee muscle strength was measured at the baseline (pre-D0) following BCAA administration for 5 days before exercise (-D5, -4D, -3D, -2D, -1D). In contrast, the post-treatment measurements (D3) were recorded after BCAA administration for 3 days (post-D0, D1, D2). Blood samples were obtained before (pre-D0), immediately after (post-D0), 24 h (D1), 48 h (D2), and 72 h (D3) after the exercise to analyze the indicators of muscle strength. BCAA was administered twice daily for 8 days (5 days and 3 days before inducing DOMS and during the experimental period, respectively). [Results] There was no difference in the flexion peak torque between the groups. However, the BCAA group showed a significantly higher extension peak torque at D3 (second isokinetic exercise), compared to the placebo group (p<.05). There was no difference in AST changes between the groups. Nonetheless, the CK and LDH were significantly reduced in the BCAA group, compared to the placebo group. There was no correlation between the extension peak torque and flexion peak torque. However, the CK and LDH increased proportionately in DOMS. Moreover, their concentrations significantly increased with a decreasing peak torque (p<.01). [Conclusion] An exercise-induced DOMS results in a decrease in the peak torque and a proportional increase in the CK and LDH concentrations. Moreover, the administration of BCAA inhibits the reduction of the extension peak torque and elevation of CK and LDH concentrations. Therefore, BCAA might be administered as a supplement to maintain the muscle strength and prevent muscle damage during vigorous exercises that may induce DOMS in sports settings.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.419-426
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• 2021

In this study, we aimed to investigate the effects of 8 weeks of treatment with a combination of evogliptin and leucine, a branched-chain amino acid, in mice with high-fat diet (HFD)-induced diabetes. Treatment with evogliptin alone or in combination with leucine reduced the body weight of the mice, compared to the case for those from the HFD control group. Long-term treatment with evogliptin alone or in combination with leucine resulted in a significant reduction in glucose intolerance; however, leucine alone did not affect postprandial glucose control, compared to the case for the mice from the HFD control group. Furthermore, the combination of evogliptin and leucine prevented HFD-induced insulin resistance, which was associated with improved homeostasis model assessment for insulin resistance, accompanied by markedly reduced liver fat deposition, hepatic triglyceride content, and plasma alanine aminotransferase levels. The combination of evogliptin and leucine increased the gene expression levels of hepatic peroxisome proliferator-activated receptor alpha, whereas those of the sterol regulatory element-binding protein 1 and stearoyl-CoA desaturase 1 were not altered, compared to the case in the HFD-fed mice (p<0.05). Thus, our results suggest that the combination of evogliptin and leucine may be beneficial for treating patients with type 2 diabetes and hepatic steatosis; however, further studies are needed to delineate the molecular mechanisms underlying the action of this combination.