Results of a study on organophosphate (OP) resistance carried out on 4 Italian field populations of Culex pipiens are reported. The A1, A4-B4 and/or A5-B5 nonspecific esterases and insensitive acetylcholinesterase (AChE) were detected in our samples. A2-B2 esterases previously recorded in Italy were not observed. The A4-B4 and/or A5-B5 esterases were first found in Italy where they are at prese...

The structure of malathion, S-[1,2-di(ethoxycarbonyl)ethyl] 00-dimethyl phosphorodithioate, has suggested to many investigators (e.g. Murphy & Dubois, 1957; Seume & O'Brien, 1960) that hydrolases may be involved in the synergism observed by Frawley, Fuyat, Hagan, Blake & Fitzhugh (1957) between malathion and O-ethyl O-p-nitrophenyl phenyl phosphorothioate. On the basis of their known substrate ...

In the fat body of Aedes aegypti a very high unspecific esterase activity and a low lipolytic activity was found. The electrophoretic isozyme patterns of the unspecific esterases show only few changes in the different physiological stages. The activity of the unspecific esterases as well as of the lipase is especially high in young sugar fed and in blood fed mosquitoes which points to special e...

BACKGROUND There has been no comprehensive study on biochemical characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus. To fill this void in the literature, a nationwide investigation was performed to quantify the enzyme activities, thereby attempting to characterize the potential resistance mechanisms in Cx. quinquefasciatus in residentia...

Glucuronoyl esterases are a novel type of enzymes believed to catalyze the hydrolysis of ester linkages between lignin and glucuronoxylan in lignocellulosic biomass, linkages known as lignin carbohydrate complexes. These complexes contribute to the recalcitrance of lignocellulose. Glucuronoyl esterases are a part of the microbial machinery for lignocellulose degradation and coupling their role ...

Comparisons among the primary sequences of five cloned eukaryotic esterases reveal two distinct lineages, neither bearing any significant overall sequence similarity to the functionally related serine protease multigene family. We have not eliminated the possibility that the esterases may have residual conformational similarities to the serine proteases. However, our profile analysis and analys...