title: Partial characterization of a malonyl-CoA-sensitive carnitine O-palmitoyltransferase I from Macrobrachium borellii (Crustacea: Palaemonidae).
abstract: The shuttle system that mediates the transport of fatty acids across the mitochondrial membrane in invertebrates has received little attention. Carnitine O-palmitoyltransferase I (EC 2.3.1.21; CPT I) is a key component of this system that in vertebrates controls long-chain fatty acid beta-oxidation. To gain knowledge on the acyltransferases in aquatic arthropods, physical, kinetic, regulatory and immunological properties of CPT of the midgut gland mitochondria of Macrobrachium borellii were assayed. CPT I optimum conditions were 34 degrees C and pH=8.0. Kinetic analysis revealed a Km for carnitine of 2180+/-281 microM and a Km for palmitoyl-CoA of 98.9+/-8.9 microM, while V(max) were 56.5+/-6.6 and 36.7+/-4.8 nmol min(-1) mg protein(-1), respectively. A Hill coefficient, n~1, indicate a Michaelis-Menten behavior. The CPT I activity was sensitive to regulation by malonyl-CoA, with an IC(50) of 25.2 microM. Electrophoretic and immunological analyses showed that a 66 kDa protein with an isoelectric point of 5.1 cross-reacted with both rat liver and muscle-liver anti CPT I polyclonal antibodies, suggesting antigenic similarity with the rat enzymes. Although CPT I displayed kinetic differences with insect and vertebrates, prawn showed a high capacity for energy generation through beta-oxidation of long-chain fatty acids.
authors.affiliation: Instituto de Investigaciones Bioquímicas de La Plata, Universidad Nacional de La Plata-CONICET CCT, Argentina.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Lavarías
authors.forename: María Y
authors.initials: MY
authors.lastname: Pasquevich
authors.forename: Marcos S
authors.initials: MS
authors.lastname: Dreon
authors.forename: Horacio
authors.initials: H
authors.lastname: Heras
mesh_terms: D000818:Animals; D002334:Carnitine O-Palmitoyltransferase / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism*; D004064:Digestive System / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D008316:Malonyl Coenzyme A / Q000378:metabolism / Q000494:pharmacology*; D008928:Mitochondria / Q000201:enzymology; D033541:Palaemonidae / Q000201:enzymology*; D051381:Rats; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D008316:Malonyl Coenzyme A; D002334:Carnitine O-Palmitoyltransferase