François R. Taravel

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Plant-seed parasite pollination mutualisms involve a specific pollinator whose larvae develop by consuming a fraction of the host plant seeds. These mutualisms are stable only if the plant can control seed destruction by the larvae. Here, we studied the chemical response of the European globeflower Trollius europaeus to infestation by an increasing number(More)
Mucosa from the duodenal and jejunal regions of pig small intestine was repeatedly freeze-thaw treated to solubilize an enzyme preparation, enriched in maltase, glucoamylase and alpha-limit dextrinase activities; isomaltase and sucrase remained essentially insoluble during the treatment. Chromatographic procedures, including ion-exchange, gel filtration and(More)
An investigation is presented of the angular dependence of 1JC,H in model compounds related to alpha-linked oligosaccharides. Values calculated by FPT formulation in the semi-empirical INDO method for models of (1----1)-, (1----2)-, (1----3)-, and (1----4)-linked disaccharides were compared, and the effect of the orientation of HO-2 was elucidated. The(More)
The solution conformation of digalacturonic acid and its sodium salt have been analyzed using nuclear magnetic resonance data and molecular mechanics calculations. The flexibility around the glycosidic linkage was characterized by calculation of the relaxed (phi, psi) potential surfaces for the isolated molecule, and also for dimethyl sulfoxide and aqueous(More)
Papain-solubilized pig intestinal sucrase-isomaltase was purified to homogeneity in a four-step process with a yield of 50%. The substrate specificities of the two enzyme activities were studied together and separately after inactivation or inhibition of one of the activities. Michaelis constants, maximum velocities and time courses of hydrolysis of several(More)
Intramolecular H-bonding interactions were investigated in solution for the threo and erythro diastereomeric forms of a guaiacyl beta-O-4 lignin model compound by using the NMR data obtained from hydroxyl protons. Temperature coefficients of the chemical shifts (ddelta/dT) and coupling constants (3J(HCOH)) were measured in aprotic and protic solutions:(More)
Rheological measurements have been used to investigate kappa-carrageenan-carob galactomannan mixed gels at different ratios, in particular for very low kappa-carrageenan concentrations. The viscoelastic properties of the gels were explored using sinusoidal tests on dynamic rheometers and compression tests between parallel plates. The properties of the(More)
C-n.m.r. spectroscopy has been used to investigate the carob galactomannan-kappa carrageenan binary gels. Starting from partially depolymerized carob samples, evidence for interaction and intermolecular binding was found by analysis of the spectra obtained in quantitative conditions and in the absolute intensity mode. From these, a reconstitution of the(More)