Biomaterial Database

4-Methyl-2-oxopentanoate oxidation by rat skeletal-muscle mitochondria. 1979

V W Van Hinsbergh, and J H Veerkamp, and J F Glatz

1. Oxidative decarboxylation of 4-methyl-2-oxopentanoate (2-oxoisocaproate) by mitochondria of rat skeletal muscle showed biphasic kinetics. Two apparent Km values of 9.1 micronM and 0.78 mM were established. In broken mitochondria the rate of oxidation was lower and only the higher apparent Km value was found. 2. Isovalerylcarnitine inhibited 4-methyl-2-oxopentanoate oxidation in the presence and absence of carnitine, but isovaleryl-CoA had no inhibitory effect. 3. Addition of ADP enhanced 4-methyl-2-oxopentanolate oxidation. Malate, succinate and 2-oxoglutarate additionally increased the rate of oxidation, but in the absence of ADP succinate and 2-oxoglutarate inhibited. 4. Addition of rotenone and simultaneous addition of carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP) and valinomycin markedly decreased 4-methyl-2-oxopentanoate oxidation. 5. These observations indicate that the branched-chain 2-oxo acid dehydrogenase complex is situated on the inner side of the mitochondrial inner membrane. 6. In mitochondria and homogenates CO2 was only produced by oxidative decarbosylation of 4-methyl-2-oxopentanoate. In intact muscle oxidation of this oxo acid proceeds more to completeness. 7. The physiological significance of intermediate formation during oxidation of branched-chain amino acids is discussed.

UI	MeSH Term	Description	Entries
D007651	Keto Acids	Carboxylic acids that contain a KETONE group.	Oxo Acids,Oxoacids,Acids, Keto,Acids, Oxo
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007930	Leucine	An essential branched-chain amino acid important for hemoglobin formation.	L-Leucine,Leucine, L-Isomer,L-Isomer Leucine,Leucine, L Isomer
D008931	Mitochondria, Muscle	Mitochondria of skeletal and smooth muscle. It does not include myocardial mitochondria for which MITOCHONDRIA, HEART is available.	Sarcosomes,Mitochondrion, Muscle,Muscle Mitochondria,Muscle Mitochondrion,Sarcosome
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
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
D002208	Caproates	Derivatives of caproic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a carboxy terminated six carbon aliphatic structure.	Hexanoates,Caproic Acid Derivatives,Caproic Acids,Hexanoic Acid Derivatives,Hexanoic Acids,Acid Derivatives, Caproic,Acid Derivatives, Hexanoic,Acids, Caproic,Acids, Hexanoic,Derivatives, Caproic Acid,Derivatives, Hexanoic Acid
D002331	Carnitine	A constituent of STRIATED MUSCLE and LIVER. It is an amino acid derivative and an essential cofactor for fatty acid metabolism.	Bicarnesine,L-Carnitine,Levocarnitine,Vitamin BT,L Carnitine
D003065	Coenzyme A		CoA,CoASH
D003653	Decarboxylation	The removal of a carboxyl group, usually in the form of carbon dioxide, from a chemical compound.	Decarboxylations