FIRST REPORT OF CARNITINE PALMITOYLTRANSFERASE ACTIVITY IN CRUSTACEANS

LAVARIAS, SABRIA MARIA LUISA; PASQUEVICH, Y.; DREON, M.; POLLERO, R.; HERAS, H.

Rosario, Argentina

Congreso; XLII Reunión de la Sociedad Argentina de Investigación Bioquímica (SAIB); 2006

Carnitine palmitoyltransferase-I (CPT-I) catalyzes the conversion of acyl-CoA to acylcarnitine at the outer mitochondrial membrane and is a key enzyme in the control of long-chain fatty acid oxidation. In a previous work, we reported an increase in the activation and b-oxidation of palmytic acid in hepatopancreas mitochondrias of the freshwater crustacean M. borellii after a chronic exposure to water soluble fraction (WSF). The aim of this work was characterized the CPT I enzymathic activity in this specie and further investigated the effect of the WSF exposure on lipid metabolism. CPT-I acitivity was assayed using palmitoil-CoA and L-carnitine as substrates and following the release of  CoA-SH spectrophotometrically by Ellman reactive reaction. We observed a linear relationship between the mitocondrial protein and the enzyme activity up to 66.7 µg/ml. A great temperature dependence was observed with an optimum value at 34°C, the optimum pH value for CPT I was 8.0. The Hill coefficient, n, was approximatly 1 using palmytoil-CoA, indicating Michaelis-Menten behavoir. The kinetics parameters, Km and Vmax were 259.6 mmol.l-1, and 76.8 nmol. min-1. mg protein-1 respectively. Finally, after 7 days exposure to a sublethal concentration of WSF (0.6 mg/l), an increase trend was observed between control and exposed shrimps.