Cholinesterase from the common prawn (Palaemon serratus) eyes: catalytic properties and sensitivity to organophosphate and carbamate compounds.
The main purpose of this study was to describe the kinetic properties of the cholinesterase (ChE) enzyme present in the eyes of the prawn Palaemon serratus, an abundant, ecological and commercially relevant species of European coastal environments. The obtained results suggest that the studied enzyme is a ChE and not a non-specific esterase, due to its apparent affinity for choline esters and the high sensitivity to eserine sulphate. This ChE displays a distinct preference for the substrate acetylthiocholine, showing a triphasic behaviour, with activation at low concentrations and inhibition by excess of substrate. Moreover, irreversible ChE inhibition by several organophosphate and carbamate compounds was characterized. All the irreversible inhibitions were homogeneous following a second-order rate reaction. The bimolecular rate constant (k(i)) values of ChE inhibition by the tested pesticides were also estimated and compared with available data from other invertebrate and vertebrate species. In conclusion, the results of the present study showed that prawn eyes possess only one ChE with typical properties of acetylcholinesterase, which is highly sensitive to the tested anti-cholinesterase compounds.
Frasco
Manuela F
MF
Laboratório de Ecotoxicologia, Departamento de Estudos de Populações, ICBAS, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Largo Prof. Abel Salazar, 2, 4099-003 Porto, Portugal. mffrasco@cimar.org
Fournier
Didier
D
Carvalho
Félix
F
Guilhermino
Lúcia
L
D000122:Acetylthiocholine / Q000378:metabolism; D000818:Animals; D002219:Carbamates / Q000493:pharmacokinetics* / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D002802:Cholinesterases / Q000187:drug effects / Q000378:metabolism*; D005123:Eye / Q000187:drug effects / Q000201:enzymology; D010755:Organophosphates / Q000493:pharmacokinetics* / Q000494:pharmacology; D033541:Palaemonidae / Q000187:drug effects / Q000201:enzymology*; D010575:Pesticides / Q000493:pharmacokinetics / Q000494:pharmacology; D013379:Substrate Specificity; D013860:Thiocholine / Q000031:analogs & derivatives / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics / Q000494:pharmacology
D002219:Carbamates; D002800:Cholinesterase Inhibitors; D010755:Organophosphates; D010575:Pesticides; D014874:Water Pollutants, Chemical; C009063:propionylthiocholine; D000122:Acetylthiocholine; D013860:Thiocholine; C027395:acetyl-beta-(methylthio)choline; D002802:Cholinesterases