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Biomedical subjects

F Ducancel

Publications and source records attributed to F Ducancel.

44 records · Page 3Linked to original sources
PubMed1990

Nucleotide sequence and structure analysis of cDNAs encoding short-chain neurotoxins from venom glands of a sea snake (Aipysurus laevis).

Two cDNAs from the sea snake Aipysurus laevis have been cloned and sequenced. They encode isoforms of short chain neurotoxins. One of them is toxin b, previously isolated from the venom of Aipysurus laevis and sequenced by Maeda and Tamiya (Biochem. J. 153, 79, 1976), whereas the other corresponds to an isoform which was not hitherto described. The two toxin sequences differ from each other by three amino-acid residues. Both cDNA structures were comparable with that previously determined in our laboratory for erabutoxin a from Laticauda semifasciata.

Animals↗
PubMed1989

Direct expression in E. coli of a functionally active protein A--snake toxin fusion protein.

We constructed a recombinant expression plasmid encoding a protein A--neurotoxin fusion protein. The fused toxin is directly expressed in the periplasmic space of Escherichia coli and can be purified in the milligram range by a single immuno-affinity step. The LD50 values of the fused toxin and native toxin are 130 and 20 nmol/kg mouse respectively. The Kd values characterizing their binding to the nicotinic acetylcholine receptor (AcChoR) are respectively 4.8 +/- 0.8 and 0.07 +/- 0.03 nM. In contrast, the fused and native toxins are equally well recognized by a toxin-specific monoclonal antibody which recognizes the AcChoR binding site. The lower toxicity of the fused toxin might result, therefore, from a steric hindrance, due to the presence of the bulky protein A moiety (mol. wt = 31 kd) rather than to a direct alteration of the 'toxic' site. The fused toxin is more immunogenic than native toxin, since 1 nmol of hybrid toxin and 14 nmol of native toxin give rise to comparable titers of antitoxin antibodies which, furthermore, are equally potent at neutralizing neurotoxicity. The work described in this paper shows that the use of fused toxins may be of paramount importance for future development of serotherapy against envenomation by snake bites.

Animals↗
PubMedDate not supplied

Functional characterization of two anti-estradiol antibodies as deduced from modelling and site-directed mutagenesis experiments.

Monoclonal antibodies are now widely used to measure the concentration of steroid hormones in human serum samples. The great development of molecular engineering techniques over the past 10 years has made possible the improvement of specificity and/or sensitivity of selected antibodies. We have obtained two monoclonal antibodies, 17E12E5 and 10G6D6, using estradiol-6-ethyl methoxy carbonyl (EMC)-bovine serum albumin (BSA) as immunogen. To tentatively improve their affinities for natural estradiol, we have initiated their structural and functional studies. For this purpose, we have cloned and sequenced the genes encoding the variable fragments of each antibody. Single chain variable fragments (scFv) were produced into the periplasmic space of E. coli using the pLIP6 expression vector. Mapping of the functional structures of both antibodies was obtained by combination of modelling and mutational analyses together with cross-reaction studies. The two binding pockets are described and models of estradiol complexed to 17E12E5 and 10G6D6 are proposed.

Amino Acid Sequence↗