Partial characterization of a malonyl-CoA-sensitive carnitine O-palmitoyltransferase I from Macrobrachium borellii (Crustacea: Palaemonidae)

SABRINA LAVARÍAS; MARÍA Y. PASQUEVICH; MARCOS S. DREON; HORACIO HERAS

COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART B, BIOCHEMISTRY & MOLECULAR BIOLOGY.

Elsevier

Año: 2009 vol. 152B p. 364 - 369

1096-4959

The shuttle system that mediates the transport of fatty acids across the mitochondrial membrane ininvertebrates has received little attention. Carnitine O-palmitoyltransferase I (EC 2.3.1.21; CPT I) is a keycomponent of this system that in vertebrates controls long-chain fatty acid β-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 °C and pH=8.0. Kinetic analysis revealed a Km for carnitine of 2180±281 μM and a Km for palmitoyl-CoA of 98.9±8.9 μM, while Vmax 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 IC50 of 25.2 μM. 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 β-oxidation of long-chain fatty acids.