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malfunction
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BCKD phosphorylation by BCKD kinase (BCKDK) inactivates BCKD and causes neurocognitive dysfunction, whereas dephosphorylation by specific phosphatase restores BCKD activity. Increased phosphorylated BCKD leads to increased BCKA accumulation causing BCKA-mediated astrocyte activation, cell death, and cognitive dysfunction as found in maple syrup urine disease
malfunction
elevated phosphorylation, and lower activity, of liver BCKDH in various models of diabetes. The decreased liver BCAA oxidation is likely mediated by post-translational inhibition of BCKDH via phosphorylation. When fed a BCAA-restricted diet, fatty acyl-CoA content in the skeletal muscle of rats decreases and insulin resistance is improved. The expression of BCAA catabolic genes has been shown to be reduced in tissue from rodent and human failing hearts
malfunction
genetic deletion in mice of BCKDHA or of a BCAA transporter specifically in brown fat is sufficient to raise plasma BCAAs. Elevated phosphorylation, and lower activity, of liver BCKDH in various models of diabetes. The decreased liver BCAA oxidation is likely mediated by post-translational inhibition of BCKDH via phosphorylation. The expression of BCAA catabolic genes has been shown to be reduced in tissue from rodent and human failing hearts
malfunction
inactivating homozygous mutations in the gene encoding BCKD kinase (BCKDK) have been identified in families with autism, epilepsy, and intellectual disability by whole exome sequencing. Affected patients show reduced plasma level of branched-chain amino acids. Disease-causing mutations in the genes encoding the subunits E1alpha, E1beta, E2, and E3 of the BCKD complex have been identified to cause the Maple syrup urine disease (MSUD), an autosomal recessive disorder usually diagnosed by newborn screening. Mutations in the subunits E1alpha, E1beta, and E2 cause MSUD types 1A, 1B, and 2, respectively. Mutations in the E3 subunit cause multiple dehydrogenase deficiency, as E3 is the subunit shared by the three 2-ketoacid dehydrogenase complexes (PDH, 2-ketoglutarate dehydrogenase and BCKD). Congenital deficiencies of enzymes involved in branched-chain amino acid metabolism: clinical phenotypes, overview
malfunction
Maple syrup urine disease (MSUD) is caused by autosomal recessive mutations in either the E1 (BCKDHA/BCKDHB) or E2 (DBT) subunits of BCKDH. Because the E3 (DLD) subunit of BCKDH is shared with PDH and OGDH, mutations in DLD cause more complex disease, and though sometimes labeled MSUD, is more appropriately labeled dihydrolipoamide dehydrogenase deficiency. Mutations in PPM1K can cause a mild variant of MSUD. Overall, disease severity is usually inversely related to residual enzyme activity. These mutations lead to elevated plasma BCAA and BCKA levels, as well as elevated urine levels of sotolone, an otherwise rare byproduct of excess leucine and isoleucine that gives urine a maple syrup-like odor. If left untreated, MSUD can cause cerebral edema, encephalopathy, and ultimately death, underscoring the importance of tight homeostatic regulation of BCAAs. Elevated phosphorylation, and lower activity, of liver BCKDH in various models of diabetes. The decreased liver BCAA oxidation is likely mediated by post-translational inhibition of BCKDH via phosphorylation. The expression of BCAA catabolic gene has been shown to be reduced in tissue from rodent and human failing hearts. BT2 might improve outcomes in heart failure either by activating oxidation in another tissue or by impacting signaling from BCAA-derived metabolites within the heart. Activation of BCKDH with 3,6-dichlorobrenzo(b)thiophene-2-carboxylic acid (BT2), a small-molecule BCKDK inhibitor, improves insulin sensitivity
malfunction
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maple syrup urine disease (MSUD) results from one or more functional mutations in the E1alpha or E1beta subunit proteins of E1 enzyme or E2 enzyme protein of BCKDC
malfunction
maple syrup urine disease (MSUD) results from one or more functional mutations in the E1alpha or E1beta subunit proteins of E1 enzyme or E2 enzyme protein of BCKDC, phenotype, overview
malfunction
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BCKD phosphorylation by BCKD kinase (BCKDK) inactivates BCKD and causes neurocognitive dysfunction, whereas dephosphorylation by specific phosphatase restores BCKD activity. Increased phosphorylated BCKD leads to increased BCKA accumulation causing BCKA-mediated astrocyte activation, cell death, and cognitive dysfunction as found in maple syrup urine disease
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metabolism
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divergent induction of branched-chain aminotransferases and phosphorylation of branched chain keto-acid dehydrogenase is a potential mechanism coupling branched-chain keto-acid-mediated-astrocyte activation to branched-chain amino acid depletion-mediated cognitive deficit after traumatic brain injury. Proposed model depicting the coordination of BCAA metabolism between the putative neuron: astrocyte and microglia postinjury, overview
metabolism
oxidation of branched-chain amino acids (BCAAs: leucine, valine, and isoleucine) is tightly regulated in mammals, distribution and regulation of whole-body BCAA oxidation, key factors influencing the flux of oxidative BCAA disposal in each tissue, detailed overview. Phosphorylation and dephosphorylation of the rate-limiting enzyme, branched-chain alpha-ketoacid dehydrogenase complex directly regulates BCAA oxidation, and various other indirect mechanisms of regulation also exist
metabolism
oxidation of branched-chain amino acids (BCAAs: leucine, valine, and isoleucine) is tightly regulated in mammals, distribution and regulation of whole-body BCAA oxidation, key factors influencing the flux of oxidative BCAA disposal in each tissue, detailed overview. Phosphorylation and dephosphorylation of the rate-limiting enzyme, branched-chain alpha-ketoacid dehydrogenase complex directly regulates BCAA oxidation, and various other indirect mechanisms of regulation also exist
metabolism
oxidation of branched-chain amino acids (BCAAs: leucine, valine, and isoleucine) is tightly regulated in mammals, distribution and regulation of whole-body BCAA oxidation, key factors influencing the flux of oxidative BCAA disposal in each tissue, detailed overview. Phosphorylation and dephosphorylation of the rate-limiting enzyme, branched-chain alpha-ketoacid dehydrogenase complex directly regulates BCAA oxidation, and various other indirect mechanisms of regulation also exist. BCAT2 and BCKDH can associate to form a metabolon, a supramolecular complex that allows substrates to channel from enzyme to enzyme. Phosphorylation of BCKDH destabilizes BCAT2's interaction with BCKDH
metabolism
the enzyme plays an important role in the catabolism of branched-chain amino acids, detailed overview
metabolism
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the initial step in the catabolism of BCAAs is reversible transamination of Leu, Ile, and Val with alpha-oxoglutarate to produce their respective branched-chain alpha-oxo acids (BCKAs), alpha-oxoisocaproate, 2-oxo-beta-methylvalerate, and 2-oxoisovalerate (KIC, KMV, and KIV, respectively) and Glu via the branched-chain aminotransferase (BCAT) isozymes. The second step is the oxidative decarboxylation of the BCKAs to produce their respective branched-chain acyl-CoA derivatives by the BCKDC. Oxidative decarboxylation of the BCKAs is highly regulated, because it commits the carbon skeleton of these amino acids to irreversible catabolism, which permits net transfer of BCAA nitrogen to Glu. BCAA catabolic pathway, overview. Mitochondrial BCATm, but not cytosolic BCATc, binds and forms a metabolon with GDH or BCKDC
metabolism
the initial step in the catabolism of BCAAs is reversible transamination of Leu, Ile, and Val with alpha-oxoglutarate to produce their respective branched-chain alpha-oxo acids (BCKAs), alpha-oxoisocaproate, 2-oxo-beta-methylvalerate, and 2-oxoisovalerate (KIC, KMV, and KIV, respectively) and Glu via the branched-chain aminotransferase (BCAT) isozymes. The second step is the oxidative decarboxylation of the BCKAs to produce their respective branched-chain acyl-CoA derivatives by the BCKDC. Oxidative decarboxylation of the BCKAs is highly regulated, because it commits the carbon skeleton of these amino acids to irreversible catabolism, which permits net transfer of BCAA nitrogen to Glu. BCAA catabolic pathway, overview. Mitochondrial BCATm, but not cytosolic BCATc, binds and forms a metabolon with GDH or BCKDC
metabolism
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divergent induction of branched-chain aminotransferases and phosphorylation of branched chain keto-acid dehydrogenase is a potential mechanism coupling branched-chain keto-acid-mediated-astrocyte activation to branched-chain amino acid depletion-mediated cognitive deficit after traumatic brain injury. Proposed model depicting the coordination of BCAA metabolism between the putative neuron: astrocyte and microglia postinjury, overview
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physiological function
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2-methylbutyric acid is produced via hydroxymethyl-glutarylcoenzyme A and acetyl-CoA, along with ATP and oxidation/reduction precursors. Lactococci contain redundant genes for branched-chain fatty acid production that are regulated by an unknown mechanism linked to carbon metabolism
physiological function
BCKDH is a member of the mitochondrial alpha-oxoacid dehydrogenase complex family, along with PDH and OGDH, which together share primary and tertiary structure, as well as likely evolutionary origin. BCKDH is a multienzyme complex made up of three components, E1, E2, and E3. E1 is a heterotetramer composed of two alpha subunits and two beta subunits, encoded by BCKDHA and BCKDHB, respectively. Despite being essential, BCAAs are surprisingly abundant and make up about 35% of essential amino acids and 18% of all amino acids in animal protein. Because BCAAs are essential, animals must balance their intake and loss. All intake comes from diet, and loss occurs through oxidation. The relative abundance of BCAAs in protein is almost always 2.2 : 1.6 : 1.0 leucine : valine : isoleucine, illustrating that the synthesis and oxidation of each individual BCAA are linked to one another. Circulating plasma levels of BCAAs in mammals remain consistent at about 0.2 mM valine, 0.1 mM leucine, and 0.06 mM isoleucine in the fasted state, after feeding, these levels rise briefly but fall back to baseline after a few hours. Together this indicates homeostatic regulation of BCAAs. Basic BCAA oxidative pathway, including a simplified structure showing the regulation of the rate-limiting enzyme, BCKDH. BCAT2 binding to BCKDH also increases BCKDH activity, while phosphorylation of BCKDH destabilizes BCAT2's interaction with BCKDH. Activation of BCKDH with BT2 improves insulin sensitivity. The redistribution of BCAA oxidation towards skeletal muscle drives insulin resistance
physiological function
BCKDH is a member of the mitochondrial alpha-oxoacid dehydrogenase complex family, along with PDH and OGDH, which together share primary and tertiary structure, as well as likely evolutionary origin. BCKDH is a multienzyme complex made up of three components, E1, E2, and E3. E1 is a heterotetramer composed of two alpha subunits and two beta subunits, encoded by BCKDHA and BCKDHB, respectively. Despite being essential, BCAAs are surprisingly abundant and make up about 35% of essential amino acids and 18% of all amino acids in animal protein. Because BCAAs are essential, animals must balance their intake and loss. All intake comes from diet, and loss occurs through oxidation. The relative abundance of BCAAs in protein is almost always 2.2 : 1.6 : 1.0 leucine : valine : isoleucine, illustrating that the synthesis and oxidation of each individual BCAA are linked to one another. Circulating plasma levels of BCAAs in mammals remain consistent at about 0.2 mM valine, 0.1 mM leucine, and 0.06 mM isoleucine in the fasted state, after feeding, these levels rise briefly but fall back to baseline after a few hours. Together this indicates homeostatic regulation of BCAAs. Basic BCAA oxidative pathway, including a simplified structure showing the regulation of the rate-limiting enzyme, BCKDH. The pancreas in mice fills nearly a third of its TCA cycle with carbons derived from BCAAs. The redistribution of BCAA oxidation towards skeletal muscle drives insulin resistance
physiological function
BCKDH is a member of the mitochondrial alpha-oxoacid dehydrogenase complex family, along with PDH and OGDH, which together share primary and tertiary structure, as well as likely evolutionary origin. BCKDH is a multienzyme complex made up of three components, E1, E2, and E3. E1 is a heterotetramer composed of two alpha subunits and two beta subunits, encoded by BCKDHA and BCKDHB, respectively. Despite being essential, BCAAs are surprisingly abundant and make up about 35% of essential amino acids and 18% of all amino acids in animal protein. Because BCAAs are essential, animals must balance their intake and loss. All intake comes from diet, and loss occurs through oxidation. The relative abundance of BCAAs in protein is almost always 2.2 : 1.6 : 1.0 leucine : valine : isoleucine, illustrating that the synthesis and oxidation of each individual BCAA are linked to one another. Circulating plasma levels of BCAAs in mammals remain consistent at about 0.2 mM valine, 0.1 mM leucine, and 0.06 mM isoleucine in the fasted state, after feeding, these levels rise briefly but fall back to baseline after a few hours. Together this indicates homeostatic regulation of BCAAs. Basic BCAA oxidative pathway, including a simplified structure showing the regulation of the rate-limiting enzyme, BCKDH. The redistribution of BCAA oxidation towards skeletal muscle drives insulin resistance
physiological function
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branched-chain amino acids are key nitrogen donors involved in interorgan and intercellular nitrogen shuttling, and Leu is an important nutrient signal. Unlike most other essential amino acids, BCAAs are initially transaminated in extrahepatic tissues via the branched-chain aminotransferases (BCAT) isozymes, followed by irreversible oxidative decarboxylation of the 2-oxo acid products, catalyzed by the branched-chain 2-oxo acid dehydrogenase enzyme complex (BCKDC), where liver is thought to be a primary site of oxidation. The BCKDC consists of multiple copies of three enzymes: (1) branched-chain 2-oxo acid dehydrogenase (E1-12 copies), (2) dihydrolipoyl transacylase (E2-24 copies), and (3) dihydrolipoyl dehydrogenase (E3-6 copies). The latter is common to all three dehydrogenase complexes. BCKDC activity is controlled via its phosphorylation state of the E1 subunits, with the phosphorylated form rendering the complex inactive. The interorgan/tissue shuttling of BCKA (and other metabolites) for complete oxidation allows for nitrogen transfer and oxidation to occur in different tissues or cells within a tissue, depending on their need for energy, metabolites, or amino acids
physiological function
branched-chain amino acids are key nitrogen donors involved in interorgan and intercellular nitrogen shuttling, and Leu is an important nutrient signal. Unlike most other essential amino acids, BCAAs are initially transaminated in extrahepatic tissues via the branched-chain aminotransferases (BCAT) isozymes, followed by irreversible oxidative decarboxylation of the 2-oxo acid products, catalyzed by the branched-chain 2-oxo acid dehydrogenase enzyme complex (BCKDC), where liver is thought to be a primary site of oxidation. The BCKDC consists of multiple copies of three enzymes: (1) branched-chain 2-oxo acid dehydrogenase (E1-12 copies), (2) dihydrolipoyl transacylase (E2-24 copies), and (3) dihydrolipoyl dehydrogenase (E3-6 copies). The latter is common to all three dehydrogenase complexes. BCKDC activity is controlled via its phosphorylation state of the E1 subunits, with the phosphorylated form rendering the complex inactive. The interorgan/tissue shuttling of BCKA (and other metabolites) for complete oxidation allows for nitrogen transfer and oxidation to occur in different tissues or cells within a tissue, depending on their need for energy, metabolites, or amino acids
physiological function
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mitochondrial 2-oxoacid dehydrogenase complexes oxidize 2-oxoglutarate, pyruvate, branched-chain 2-oxoacids and 2-oxoadipate to the corresponding acyl-CoAs and reduce NAD+ to NADH. The isolated enzyme complexes generate superoxide anion radical or hydrogen peroxide in defined reactions by leaking electrons to oxygen. But the 2-oxoacid dehydrogenase complexes contribute little to the production of superoxide or hydrogen peroxide relative to other mitochondrial sites at physiological steady-states. The contributions may increase under pathological conditions, in accordance with the high maximum capacities of superoxide or hydrogen peroxide-generating reactions of the complexes, established in isolated mitochondria. The complexes consist of multiple copies of three catalytic components (E1, E2 and E3). The first step of the overall complex reaction is catalyzed by the appropriate 2-oxoacid specific 2-oxoacid dehydrogenase (E1). Employing the diphosphorylated derivative of vitamin B1, ThDP, the E1 components decarboxylate 2-oxoacids to the first reaction product CO2 and ThDP-bound active aldehydes. The decarboxylation reaction is followed by the reductive acylation of the E1 substrate-acceptor, the lipoyl-comprising domain of the second component (E2) of the complexes. E1-catalyzed reaction releasing CO2 is irreversible, and has specific significance in the regulation of the overall process. Formation of the active aldehyde after decarboxylation of an adduct of a 2-oxoacid with thiamine diphosphate in the active site of E1 is a pre-requisite for the ROS-generating reactions by the E1 component and for the physiological reduction of the complex-bound dihydrolipoyl residues, participating in the forward direction of ROS generation by the complexes, overview. The dehydrogenase components E1 and E3 catalyze generation of superoxide and/or hydrogen peroxide in both the isolated and complex-bound state, albeit to different degrees
physiological function
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mitochondrial 2-oxoacid dehydrogenase complexes oxidize 2-oxoglutarate, pyruvate, branched-chain 2-oxoacids and 2-oxoadipate to the corresponding acyl-CoAs and reduce NAD+ to NADH. The isolated enzyme complexes generate superoxide anion radical or hydrogen peroxide in defined reactions by leaking electrons to oxygen. But the 2-oxoacid dehydrogenase complexes contribute little to the production of superoxide or hydrogen peroxide relative to other mitochondrial sites at physiological steady-states. The contributions may increase under pathological conditions, in accordance with the high maximum capacities of superoxide or hydrogen peroxide-generating reactions of the complexes, established in isolated mitochondria. The complexes consist of multiple copies of three catalytic components (E1, E2 and E3). The first step of the overall complex reaction is catalyzed by the appropriate 2-oxoacid specific 2-oxoacid dehydrogenase (E1). Employing the diphosphorylated derivative of vitamin B1, ThDP, the E1 components decarboxylate 2-oxoacids to the first reaction product CO2 and ThDP-bound active aldehydes. The decarboxylation reaction is followed by the reductive acylation of the E1 substrate-acceptor, the lipoyl-comprising domain of the second component (E2) of the complexes. E1-catalyzed reaction releasing CO2 is irreversible, and has specific significance in the regulation of the overall process. Formation of the active aldehyde after decarboxylation of an adduct of a 2-oxoacid with thiamine diphosphate in the active site of E1 is a pre-requisite for the ROS-generating reactions by the E1 component and for the physiological reduction of the complex-bound dihydrolipoyl residues, participating in the forward direction of ROS generation by the complexes, overview. The dehydrogenase components E1 and E3 catalyze generation of superoxide and/or hydrogen peroxide in both the isolated and complex-bound state, albeit to different degrees
physiological function
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mitochondrial 2-oxoacid dehydrogenase complexes oxidize 2-oxoglutarate, pyruvate, branched-chain 2-oxoacids and 2-oxoadipate to the corresponding acyl-CoAs and reduce NAD+ to NADH. The isolated enzyme complexes generate superoxide anion radical or hydrogen peroxide in defined reactions by leaking electrons to oxygen. But the 2-oxoacid dehydrogenase complexes contribute little to the production of superoxide or hydrogen peroxide relative to other mitochondrial sites at physiological steady-states. The contributions may increase under pathological conditions, in accordance with the high maximum capacities of superoxide or hydrogen peroxide-generating reactions of the complexes, established in isolated mitochondria. The complexes consist of multiple copies of three catalytic components (E1, E2 and E3). The first step of the overall complex reaction is catalyzed by the appropriate 2-oxoacid specific 2-oxoacid dehydrogenase (E1). Employing the diphosphorylated derivative of vitamin B1, ThDP, the E1 components decarboxylate 2-oxoacids to the first reaction product CO2 and ThDP-bound active aldehydes. The decarboxylation reaction is followed by the reductive acylation of the E1 substrate-acceptor, the lipoyl-comprising domain of the second component (E2) of the complexes. E1-catalyzed reaction releasing CO2 is irreversible, and has specific significance in the regulation of the overall process. Formation of the active aldehyde after decarboxylation of an adduct of a 2-oxoacid with thiamine diphosphate in the active site of E1 is a pre-requisite for the ROS-generating reactions by the E1 component and for the physiological reduction of the complex-bound dihydrolipoyl residues, participating in the forward direction of ROS generation by the complexes, overview. The dehydrogenase components E1 and E3 catalyze generation of superoxide and/or hydrogen peroxide in both the isolated and complex-bound state, albeit to different degrees
physiological function
mitochondrial 2-oxoacid dehydrogenase complexes oxidize 2-oxoglutarate, pyruvate, branched-chain 2-oxoacids and 2-oxoadipate to the corresponding acyl-CoAs and reduce NAD+ to NADH. The isolated enzyme complexes generate superoxide anion radical or hydrogen peroxide in defined reactions by leaking electrons to oxygen. But the 2-oxoacid dehydrogenase complexes contribute little to the production of superoxide or hydrogen peroxide relative to other mitochondrial sites at physiological steady-states. The contributions may increase under pathological conditions, in accordance with the high maximum capacities of superoxide or hydrogen peroxide-generating reactions of the complexes, established in isolated mitochondria. The complexes consist of multiple copies of three catalytic components (E1, E2 and E3). The first step of the overall complex reaction is catalyzed by the appropriate 2-oxoacid specific 2-oxoacid dehydrogenase (E1). Employing the diphosphorylated derivative of vitamin B1, ThDP, the E1 components decarboxylate 2-oxoacids to the first reaction product CO2 and ThDP-bound active aldehydes. The decarboxylation reaction is followed by the reductive acylation of the E1 substrate-acceptor, the lipoyl-comprising domain of the second component (E2) of the complexes. E1-catalyzed reaction releasing CO2 is irreversible, and has specific significance in the regulation of the overall process. Formation of the active aldehyde after decarboxylation of an adduct of a 2-oxoacid with thiamine diphosphate in the active site of E1 is a pre-requisite for the ROS-generating reactions by the E1 component and for the physiological reduction of the complex-bound dihydrolipoyl residues, participating in the forward direction of ROS generation by the complexes, overview. The dehydrogenase components E1 and E3 catalyze generation of superoxide and/or hydrogen peroxide in both the isolated and complex-bound state, albeit to different degrees
physiological function
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the BCKA dehydrogenase (BCKD) complex catalyzes the irreversible oxidative decarboxylation of BCKAs to produce branched-chain acyl-CoA intermediates, which then follow separate catabolic pathways. Branched-chain keto-acids (BCKAs) are metabolized by the mitochondrial branched-chain keto-acid dehydrogenase (BCKD) whose activity is regulated by its phosphorylation state. BCKD phosphorylation by BCKD kinase (BCKDK) inactivates BCKD and causes neurocognitive dysfunction, whereas dephosphorylation by specific phosphatase restores BCKD activity. Brain BCKD activity is dynamically regulated by the balance between its phosphorylation and dephosphorylation cycle
physiological function
the BKDH complex is a multienzyme complex composed of three catalytic components: a thiamine diphosphate-dependent decarboxylase/dehydrogenase (E1), a lipoyl transacylase (E2), and a dihydrolipoamide dehydrogenase (E3)
physiological function
the enzyme system catalyses the oxidative decarboxylation of branched-chain alpha-oxo acids derived from L-leucine, L-isoleucine, and L-valine to branched-chain acyl-CoAs. It belongs to the 2-oxoacid dehydrogenase system family, which also includes EC 1.2.1.104, pyruvate dehydrogenase system, EC 1.2.1.105, 2-oxoglutarate dehydrogenase system, EC 1.4.1.27, glycine cleavage system, and EC 2.3.1.190, acetoin dehydrogenase system. The BCKD complex is a multiprotein enzyme composed of three subunits, E1, E2, and E3. A kinase and a phosphatase are attached to the E1 subunit and regulate the complex activity. The E2 subunit constitutes the center of the complex to which the E1 and E3 components are attached. The E2 subunit consists of 24 identical elements, being a homo-24-meric structure that has three domains: the core domain, the binding domain, and the lipoyl domain (lipoic acid bearing domain). The binding domain attaches the subunits E1 and E3 to E2. The lipoyl domain is essential to substrate channeling within the complex. The core domain contains the active site. The E1 subunit of the BCKD complex is a tetramer composed of two alpha and two beta components (alpha2beta2). E1 is the BCKD complex component, which catalyze the oxidative decarboxylation of branched-chain oxoacid substrates. E1 binds thiamine diphosphate, possessing two thiamine-binding pockets located between alpha and beta subunits. The crystal structure of the E1 subunit has been determined, showing a tetrahedral arrangement of the two alpha and two beta subunits. The branched-chain ketoacid dehydrogenase (BCKD) complex catalyzes the irreversible oxidative decarboxylation of branched-chain ketoacids to produce branched-chain acyl-coenzyme A (coA) derivative esters, which undergo separate catabolic pathways depending on the initial substrate. Ultimately, leucine renders acetoacetate and acetyl-CoA, isoleucine yields propionyl-CoA and acetyl-CoA and the end product of valine catabolism is propionyl-CoA. The activity of the BCKD complex is regulated by phosphorylation and dephosphorylation catalyzed by a kinase and a phosphatase, respectively. The BCKD kinase inhibits the complex whereas the BCKD phosphatase activates it
physiological function
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2-methylbutyric acid is produced via hydroxymethyl-glutarylcoenzyme A and acetyl-CoA, along with ATP and oxidation/reduction precursors. Lactococci contain redundant genes for branched-chain fatty acid production that are regulated by an unknown mechanism linked to carbon metabolism
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physiological function
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the BCKA dehydrogenase (BCKD) complex catalyzes the irreversible oxidative decarboxylation of BCKAs to produce branched-chain acyl-CoA intermediates, which then follow separate catabolic pathways. Branched-chain keto-acids (BCKAs) are metabolized by the mitochondrial branched-chain keto-acid dehydrogenase (BCKD) whose activity is regulated by its phosphorylation state. BCKD phosphorylation by BCKD kinase (BCKDK) inactivates BCKD and causes neurocognitive dysfunction, whereas dephosphorylation by specific phosphatase restores BCKD activity. Brain BCKD activity is dynamically regulated by the balance between its phosphorylation and dephosphorylation cycle
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additional information
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anaerobic radical intermediate of E1-bound active aldehyde has been trapped by 5,5-dimethyl-1-pyrroline N-oxide (DMPO), which can serve as an artificial substrate-acceptor in the reaction
additional information
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anaerobic radical intermediate of E1-bound active aldehyde has been trapped by 5,5-dimethyl-1-pyrroline N-oxide (DMPO), which can serve as an artificial substrate-acceptor in the reaction
additional information
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anaerobic radical intermediate of E1-bound active aldehyde has been trapped by 5,5-dimethyl-1-pyrroline N-oxide (DMPO), which can serve as an artificial substrate-acceptor in the reaction
additional information
anaerobic radical intermediate of E1-bound active aldehyde has been trapped by 5,5-dimethyl-1-pyrroline N-oxide (DMPO), which can serve as an artificial substrate-acceptor in the reaction