Biomaterial Database

Long-chain acyl-CoA synthetase and "outer" carnitine long-chain acyltransferase activities of intact brown adipose tissue mitochondria. 1978

P T Normann, and T Flatmark

1. The activities of long-chain acyl-CoA synthetase (acid: CoA ligase (AMP-forming), EC 6.2.1.3) and the "outer" carnitine long-chain acyltransferase (palmitoyl-CoA: L-carnitine O-palmitoyltransferase, EC 2.3.1.21) have been estimated in intact brown adipose tissue mitochondria. The assay of both enzymes is based on a coupled reaction in which the intramitochondrial (matrix) CoASH is the final acyl acceptor and the oxidation-reduction state of the flavoproteins in the acyl-CoA dehydrogens pathway is used to determine the intramitochondrial level of acyl-CoA. 2. Using endogenous fatty acids as the substrate, the progress curve of acyl-CoA synthetase activity was in most mitochondrial preparations linear within the first 30 s. When initial rates were measured, the Km value for CoASH (2.4 micron) was lower than previously determined for the acyl-CoA synthetase in brown adipose tissue mitochondria as well as in mitochondria of other tissues. The pH activity curve indicates that the unprotonated form of the fatty acids represents the substrate of acyl-CoA synthetase, i.e. similar to the effect of pH on the binding of fatty acids to bovine serum albumin. 3. Experimental evidence is presented that at temperatures higher than the transition temperature of the acyl-CoA synthetase (i.e. Tt = 19 degrees C), this enzymic reaction is rate-limiting in the sequence of coupled reactions leading to beta-oxidation in the mitochondrial matrix. 4. The initial rate of the long-chain acyl-COA synthetase reaction was estimated to v = 119 +/- 16 nmol . min-1 . mg-1 protein (mean +/- S.D., n = 5) at an optimal concentration of palmitate which exceeds that of rat heart mitochondria by a factor of 10.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D002001	Adipose Tissue, Brown	A thermogenic form of adipose tissue composed of BROWN ADIPOCYTES. It is found in newborns of many species including humans, and in hibernating mammals. Brown fat is richly vascularized, innervated, and densely packed with MITOCHONDRIA which can generate heat directly from the stored lipids.	Brown Fat,Hibernating Gland,Brown Adipose Tissue,Fat, Brown,Tissue, Brown Adipose
D002334	Carnitine O-Palmitoyltransferase	An enzyme that catalyzes reversibly the conversion of palmitoyl-CoA to palmitoylcarnitine in the inner mitochondrial membrane. EC 2.3.1.21.	Carnitine Palmitoyltransferase,CPT II,Carnitine Acyltransferase I,Carnitine Palmitoyltransferase I,Carnitine Palmitoyltransferase II,Palmitoylcarnitine Transferase,Palmitylcarnitine Acyltransferase,Acyltransferase I, Carnitine,Acyltransferase, Palmitylcarnitine,Carnitine O Palmitoyltransferase,II, Carnitine Palmitoyltransferase,O-Palmitoyltransferase, Carnitine,Palmitoyltransferase I, Carnitine,Palmitoyltransferase II, Carnitine,Palmitoyltransferase, Carnitine,Transferase, Palmitoylcarnitine
D003066	Coenzyme A Ligases	Enzymes that catalyze the formation of acyl-CoA derivatives. EC 6.2.1.	Acyl CoA Synthetase,Acyl CoA Synthetases,Acyl Coenzyme A Synthetase,Acyl Coenzyme A Synthetases,Coenzyme A Ligase,Coenzyme A Synthetase,Coenzyme A Synthetases,Acid-Thiol Ligases,Co A Ligases,A Ligase, Coenzyme,A Synthetase, Coenzyme,Acid Thiol Ligases,CoA Synthetase, Acyl,CoA Synthetases, Acyl,Ligase, Coenzyme A,Ligases, Acid-Thiol,Ligases, Co A,Ligases, Coenzyme A,Synthetase, Acyl CoA,Synthetase, Coenzyme A,Synthetases, Acyl CoA,Synthetases, Coenzyme A
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D000217	Acyltransferases	Enzymes from the transferase class that catalyze the transfer of acyl groups from donor to acceptor, forming either esters or amides. (From Enzyme Nomenclature 1992) EC 2.3.	Acyltransferase
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus