Partial characterization of a malonyl-CoA-sensitive carnitine o-palmitoyltransferase I from Macrobrachium borellii. (Crustacea: Palaemomidae)

LAVARÍAS, S.; PASQUEVICH, M.Y.; DREON, M.S.; HERAS, H.

COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY

Elsevier

Año: 2009 vol. 152 p. 364 - 369

0010-406X

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 b-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 2,180 ± 281 mM and a Km for palmitoyl-CoA of 98.9 ± 8.9  mM, 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 b-oxidation of long-chain fatty acids.