| isovaleryl-CoA dehydrogenase | |||||||||
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Isovaleryl-CoA dehydrogenase tetramer, Human
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| Identifiers | |||||||||
| EC no. | 1.3.8.4 | ||||||||
| CAS no. | 37274-61-6 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
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Inenzymology, an isovaleryl-CoA dehydrogenase (EC 1.3.8.4) is an enzyme that catalyzes the chemical reaction
3-methylbut-2-enoyl-CoA + reduced acceptorThus, the two substrates of this enzyme are 3-methylbutanoyl-CoA and acceptor, whereas its two products are 3-methylbut-2-enoyl-CoA and reduced acceptor.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with other acceptors. The systematic name of this enzyme class is 3-methylbutanoyl-CoA:acceptor oxidoreductase. Other names in common use include isovaleryl-coenzyme A dehydrogenase, isovaleroyl-coenzyme A dehydrogenase, and 3-methylbutanoyl-CoA:(acceptor) oxidoreductase. This enzyme participates in valine, leucine and isoleucine degradation. It employs one cofactor, FAD.
As of late 2007, only one structure has been solved for this class of enzymes, with the PDB accession code 1IVH. It was created by a group containing K.A.Tiffany, D.L.Roberts, M.Wang, R.Paschke, A.-W.A.Mohsen, J.Vockley, and J.J.P.Kim. The structure was released on May 20, 1998.Doe. "PDBsum entry: 1ivh". Retrieved November 25, 2019.
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Muscle: α-Ketoisocaproate (α-KIC)
Liver: α-Ketoisocaproate (α-KIC)
Excreted
in urine (10–40%)
β-Hydroxy β-methylglutaryl-CoA
(HMG-CoA)
β-Methylcrotonyl-CoA
(MC-CoA)
β-Methylglutaconyl-CoA
(MG-CoA)
Isovaleryl-CoA
dehydrogenase
Unknown
enzyme
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HMB is a metabolite of the amino acid leucine (Van Koverin and Nissen 1992), an essential amino acid. The first step in HMB metabolism is the reversible transamination of leucine to [α-KIC] that occurs mainly extrahepatically (Block and Buse 1990). Following this enzymatic reaction, [α-KIC] may follow one of two pathways. In the first, HMB is produced from [α-KIC] by the cytosolic enzyme KIC dioxygenase (Sabourin and Bieber 1983). The cytosolic dioxygenase has been characterized extensively and differs from the mitochondrial form in that the dioxygenase enzyme is a cytosolic enzyme, whereas the dehydrogenase enzyme is found exclusively in the mitochondrion (Sabourin and Bieber 1981, 1983). Importantly, this route of HMB formation is direct and completely dependent of liver KIC dioxygenase. Following this pathway, HMB in the cytosol is first converted to cytosolic β-hydroxy-β-methylglutaryl-CoA (HMG-CoA), which can then be directed for cholesterol synthesis (Rudney 1957) (Fig. 1). In fact, numerous biochemical studies have shown that HMB is a precursor of cholesterol (Zabin and Bloch 1951; Nissen et al. 2000).
Energy fuel: Eventually, most Leu is broken down, providing about 6.0kcal/g. About 60% of ingested Leu is oxidized within a few hours ... Ketogenesis: A significant proportion (40% of an ingested dose) is converted into acetyl-CoA and thereby contributes to the synthesis of ketones, steroids, fatty acids, and other compounds
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