Showing papers by "Debabrata Chatterjee published in 2003"

Interaction of [RuIII(edta)(H2O)]− with amino acids in aqueous solution. Equilibrium, kinetic and protease inhibition studies

Abstract: The interaction of [RuIII(edta)(H2O)]− (edta = ethylenediaminetetraacetate) with amino acids, viz. glycine, L-cysteine and S-methylcysteine, was investigated potentiometrically and kinetically. The concentration distribution of various complex species was evaluated as a function of pH. Kinetic data obtained as a function of [amino acid], temperature (5.0 to 45.0 °C) and pressure at a fixed pH of 6.0, reveal that the formation of [RuIII(edta)(Am)]− (Am = amino acid) occurs via a rapid amino acid concentration dependent complex-formation reaction of [RuIII(edta)(H2O)]−, followed by a slow amino acid concentration independent ring-closure step. The kinetic data and activation parameters are interpreted in terms of an associative interchange mechanism and discussed in reference to data reported for closely related systems in the literature. Enzyme inhibition studies revealed that [RuIII(edta)(H2O)]− effectively inhibits the cysteine protease activity in papain and bromalein enzymes.

Photodegradation of surfactants on the dye modified TiO 2 surface using visible light

Abstract: Degradation of cationic CPC (cetyl pyridinium chloride), anionic DBS (sodium dodecylbenzene sulfonate) and neutral Triton-X 100 (octylphenyl polyoxyethylene ether) surfactants in air-equilibrated aqueous mixtures has beenachieved on the surface of TiO 2 semiconductor modified with Thionine, Eosin Y and Nile blue A by using visible light. Under 8 hr of irradiation with a 50W tungsten lamp, over 45-65% degradation of surfactants has been observed. A working mechanism involving excitation of surface adsorbed dye, followed by charge injection into the TiO 2 conduction band and formation of reactive *OH radicals is proposed.