Cholinesterase activities of Dreissena polymorpha were measured calorimetrically. In homogenates of whole control mussel, activities of 125 f29 pmol min-’ kg-’ were found (n=6). Neither after exposure of Dreissena to organophosphates (thiometon, disulfoton, demeton-Smethyl) nor after addition of demeton-S-methyl (the activated oxygen analogue of thiometon) in vitro was the measured mussel ester...

The means by which superfamilies of specialized enzymes arise by gene duplication and functional divergence are poorly understood. The escape from adaptive conflict hypothesis, which posits multiple copies of a gene encoding a primitive inefficient and highly promiscuous generalist ancestor, receives support from experiments showing that resurrected ancestral enzymes are indeed more substrate-p...

The calcein-AM (calcein-acetoxymethyl ester) method is a widely used technique that is supposed to assay the intracellular 'labile iron pool' (LIP). When cells in culture are exposed to this ester, it passes the plasma membrane and reacts with cytosolic unspecific esterases. One of the reaction products, calcein, is a fluorochrome and a hydrophilic alcohol to which membranes are non-permeable a...

Biochemical analysis was performed on field caught Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus (Diptera: Culicidae) mosquitoes to determine activities of enzymes including mixed function oxidases (MFO), nonspecific esterases (alpha- and beta-), glutathione-S-transferases (GST), and insensitive acetylcholinesterase (AChE). Biochemical tests were performed on F1 generation of Ae. a...

Fluorescent molecules are essential for basic research in the biological sciences and have numerous practical applications. Herein is described the synthesis and use of a new class of latent fluorophores based on a novel design element, the trimethyl lock, that confers distinct advantages over extant fluorophores and pro-fluorophores. A diacetyl version of the latent fluorophore is stable in a ...

A dimeric esterase of a lycaenid butterfly shows rich, electrophoretically-detectable variation in natural populations in Texas. This isozyme variation is controlled by multiple alleles at an autosomal locus (Es-d). In each population sampled there are 9-14 alleles, two of which (Es-d(100) and Es-d(80)) predominate and form about 84% of the gene pool. Against the background of numerous rarer al...

In previous reports from this laboratory investigations of the specific esterase activity of trypsin (1) and of the detailed kinetics of the hydrolysis of specific substrates by chymotrypsin and by carboxypeptidsse have been reported (2, 3). In the present paper a reinvestigation of the kinetics of the action of trypsin on benzoyl-L-argininamide and the results of kinetic studies of the action ...

Dedicated to Prof. Rolf D. Schmid on the occasion of his 60 th birthday [**] We thank Prof. R. discussions and Sandra Vorlová (ITB) for providing recombinant hAChE and bAChE.

Proteins in the serine esterase family are widely distributed in bacterial phyla and display activity against a range of biologically produced and chemically synthesized esters. A serine esterase from the psychrophilic bacterium Pseudoalteromonas arctica with a C-terminal OsmC-like domain was recently characterized; here we report on the identification and characterization of further putative e...

Increased hydrolytic metabolism of organophosphate insecticides has been associated with resistance among Nebraska western corn rootworm populations. In this study, resistance-associated esterases were partially purified by differential centrifugation, ion exchange, and hydroxyapatite column chromatography, with a final purification factor of 100-fold and recovery of approximately 10%. Kinetic ...