Biomaterial Database

Oxidative decarboxylation of 4-methylthio-2-oxobutyrate by branched-chain 2-oxo acid dehydrogenase complex. 1986

S M Jones, and S J Yeaman

Highly purified branched-chain 2-oxo acid dehydrogenase complex (BCOADC) oxidizes 4-methylthio-2-oxobutyrate and 2-oxobutyrate, with Km values of 67 microM and 18 microM respectively. The Vmax. for oxidation of these substrates is 27% and 53% respectively of that for 3-methyl-2-oxobutyrate. Highly purified pyruvate dehydrogenase complex (PDC) oxidizes 2-oxobutyrate (Km 100 microM; Vmax. 49% of that for pyruvate) but not 4-methylthio-2-oxobutyrate, whereas 2-oxoglutarate dehydrogenase complex will not utilize either 2-oxo acid as substrate. BCOADC kinase is inhibited by both 4-methylthio-2-oxobutyrate and 2-oxobutyrate, with half-maximal inhibition by 45 microM and 50 microM respectively. Phosphorylation of BCOADC in isolated adipocytes is inhibited by both 4-methylthio-2-oxobutyrate and 2-oxobutyrate, consistent with their inhibitory action of BCOADC kinase. Phosphorylation of PDC is decreased by 2-oxobutyrate, but not by 4-methylthio-2-oxobutyrate.

UI	MeSH Term	Description	Entries
D007658	Ketone Oxidoreductases	Oxidoreductases that are specific for KETONES.	Oxidoreductases, Ketone
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008715	Methionine	A sulfur-containing essential L-amino acid that is important in many body functions.	L-Methionine,Liquimeth,Methionine, L-Isomer,Pedameth,L-Isomer Methionine,Methionine, L Isomer
D009097	Multienzyme Complexes	Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates. They may involve simply a transfer of water molecules or hydrogen atoms and may be associated with large supramolecular structures such as MITOCHONDRIA or RIBOSOMES.	Complexes, Multienzyme
D010084	Oxidation-Reduction	A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).	Redox,Oxidation Reduction
D011768	Pyruvate Dehydrogenase Complex	A multienzyme complex responsible for the formation of ACETYL COENZYME A from pyruvate. The enzyme components are PYRUVATE DEHYDROGENASE (LIPOAMIDE); dihydrolipoamide acetyltransferase; and LIPOAMIDE DEHYDROGENASE. Pyruvate dehydrogenase complex is subject to three types of control: inhibited by acetyl-CoA and NADH; influenced by the energy state of the cell; and inhibited when a specific serine residue in the pyruvate decarboxylase is phosphorylated by ATP. PYRUVATE DEHYDROGENASE (LIPOAMIDE)-PHOSPHATASE catalyzes reactivation of the complex. (From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed)	Complex, Pyruvate Dehydrogenase,Dehydrogenase Complex, Pyruvate
D003653	Decarboxylation	The removal of a carboxyl group, usually in the form of carbon dioxide, from a chemical compound.	Decarboxylations
D000090	Acetoacetates	Salts and derivatives of acetoacetic acid.
D000273	Adipose Tissue	Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.	Fatty Tissue,Body Fat,Fat Pad,Fat Pads,Pad, Fat,Pads, Fat,Tissue, Adipose,Tissue, Fatty
D042942	3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)	A ketone oxidoreductase that catalyzes the overall conversion of alpha-keto acids to ACYL-CoA and CO2. The enzyme requires THIAMINE DIPHOSPHATE as a cofactor. Defects in genes that code for subunits of the enzyme are a cause of MAPLE SYRUP URINE DISEASE. The enzyme was formerly classified as EC 1.2.4.3.	2-Oxoisovalerate Dehydrogenase (Lipoamide),2-Oxoisocaproate Dehydrogenase,Alpha-Keto Acid Dehydrogenase,BCKA Decarboxylase,Branched Chain Alpha-Keto Acid Decarboxylase,Branched Chain Ketoacid Dehydrogenase,Branched-Chain 2-Oxo Acid Dehydrogenase,Branched-Chain Keto Acid Dehydrogenase,Branched-Chain Oxo-Acid Dehydrogenase,2 Oxoisocaproate Dehydrogenase,Acid Dehydrogenase, Alpha-Keto,Alpha Keto Acid Dehydrogenase,Branched Chain 2 Oxo Acid Dehydrogenase,Branched Chain Alpha Keto Acid Decarboxylase,Branched Chain Keto Acid Dehydrogenase,Branched Chain Oxo Acid Dehydrogenase,Decarboxylase, BCKA,Dehydrogenase, 2-Oxoisocaproate,Dehydrogenase, Alpha-Keto Acid,Dehydrogenase, Branched-Chain Oxo-Acid,Oxo-Acid Dehydrogenase, Branched-Chain