Production and characterization of monoclonal antibodies against urea derivatives

Cloning and characterization of a single chain antibody to glucose oxidase from a murine hybridoma

Glucose oxidase (GOD) is an oxidoreductase catalyzing the reaction of glucose and oxygen to peroxide and gluconolacton (EC 1.1.3.4.). GOD is a widely used enzyme in biotechnology. Therefore the production of monoclonal antibodies and antibody fragments to GOD are of interest in bioanalytics and even tumor therapy. We describe here the generation of a panel of monoclonal antibodies to native and heat inactivated GOD. One of the hybridomas, E13BC8, was used for cloning of a single chain antibody (scFv). This scFv was expressed in Escherichia coli XL1-blue with the help of the vector system pOPE101. The scFv was isolated from the periplasmic fraction and detected by western blotting. It reacts specifically with soluble active GOD but does not recognize denatured GOD adsorbed to the solid phase. The same binding properties were also found for the monoclonal antibody E13BC8.

Characterization of protein conjugates using capillary electrophoresis

With the aim of generating antibodies, a calix[4]arene-crown-6 was coupled to bovine serum albumin. For that purpose, a complete procedure to optimize and characterize the coupling of hydrophobic haptens based on capillary electrophoresis (CE) was developed. We demonstrated the existence of a polynomial relationship between the electrophoretic mobility (mu(ep)) and the hapten density. This correlation was used not only to study the coupling reaction in terms of optimization and kinetics but also to determine the average coupling molar ratio of any given conjugate. An estimation of the heterogeneity of these conjugates by simulation of experimental peaks was also proposed.

Quantitative determination of diuron in ground and surface water by time-resolved fluoroimmunoassay: seasonal variations of diuron, carbofuran, and paraquat in an agricultural area

The aim of this research is to develop an ultrasensitive time-resolved fluorescence immunoassay (TR-FIA) for herbicide diuron in water samples. This method appears to be a promising approach, instead of conventional analytical techniques, in the screening procedure of organic pollutants because it is simple, rapid, and specific, and it does not require sample preconcentration or cleanup. Lanthanide chelate used as label allows to achieve sensitivity even 10 times higher than most of the other techniques. It has been applied to monitoring diuron contamination in specimens collected along a year in an agricultural area. The water specimens were collected monthly from lake, well, and irrigation ditch in the agricultural area south of Milan. Assay was performed using diuron-specific polyclonal antibody raised in sheep; as fluorescent marker, we used rabbit antisheep IgG conjugated with a chelating molecule complexed with Eu3+. The compound 4-(3-(3,4-dichloro-phenyl)-1-methyl-ureido)-butyric acid (CPD) was synthesized and conjugated with bovine serum albumin (BSA) to prepare a solid phase. Sensitivity achieved was 20 ng L-1 below the European Community limits. Paraquat (PQ) and carbofuran (CF) presence in the same samples has been also evaluated in a similar way, using immunoassays with time-resolved revelation systems. Diuron concentration shows a peak coinciding with a peak of carbofuran during summer periods. The peak of diuron was 65 pg/mL in June and 180 pg/mL in September in ditch and lake water samples, respectively; carbofuran concentration was higher than diuron in all samples: a carbofuran peak was revealed in September and October resulting in 87 ng/mL. Herbicide paraquat was not detectable in any assayed sample.

Monoclonal anti-diuron antibodies prevent inhibition of photosynthesis by diuron

Two monoclonal anti-diuron antibodies were generated that bind to diuron with an extremely low equilibrium dissociation constant. The antibodies prevented and restored in vitro and in vivo the diuron-dependent inhibition of photosynthesis. In isolated thylakoids prepared from spinach leaves (Spinacia oleracea L.) the diuron-inhibited Hill reaction was reconstituted immediately after the addition of the monoclonal antibodies. The antibodies also restored the diuron-dependent inhibition of the photosynthetic oxygen evolution of the cell wall-deficient mutant cw15 of the green alga Chlamydomonas reinhardtii Dangeard.