Monserrat_2002_Mar.Environ.Res_54_781

The aim of this work was to characterize the cholinesterases from gills of Crassostrea rhizophorae in order to use them as biomarkers. Gills were homogenized and then centrifuged (9,000 x g, 4 degrees C, 30 min). S9 and Triton X-100 S9 treated (TX S9) fractions were employed as enzyme source. Km(ap) and Vmax were estimated, using acetylthiocholine iodide as substrate. Inhibition assays were performed with iso-OMPA and eserine. The Km(ap) for S9 and TX S9 fractions were 0.05 and 0.06 mM, whereas the Vmax were 1.92 and 5.84 nmol/min/mg protein. respectively. No inhibition was detected when the samples were incubated with iso-OMPA, suggesting the presence of acetylcholinesterases (AChE) in oyster gill homogenates. Sensitivity to eserine inhibition of AChE in the gills of oysters is intermediate when compared with other aquatic species.