1,721,032 research outputs found
Electrocatalytic oxidation of dihydronicotinamide adenine dinucleotide with ferrocene carboxylic acid by diaphorase from Clostridium Kluveri. Remarks on the kinetic approaches usually adopted
No full textThe kinetics of the electron transfer between NADH and ferrocenecarboxylic acid (FMCA) catalyzed by diaphorase from Clostridium kluveri (EC 1.8.1.4.) was studied by voltammetry. A commercially available digital simulation program permitted one to determine the rate constants of the catalytic system by a fitting procedure. A rate constant of 3×104 M−1 s−1was found for the reaction between diaphorase and mediator while a value of 8 M−1 s−1was found for the parallel competitive reaction between NADH and mediator. In addition a comparison of the present method to other data treatment procedures reported in the literature and a brief evaluation of their limits of applicability were carried out
Description and validation of an analytical method for the determination of paromomicyn sulfate in medicated animal feeds
No full textA procedure for the extraction of paromomycin from different animal feed matrices (rabbit, chicken, pig feeds) and its subsequent determination via a reversed-phase ion-pair HPLC separation coupled with pulsed amperometric detection is described. The procedure optimised in terms of the extracting solvent and the solid phase extraction stationary phase allows the total recovery of the aminoglycoside antibiotic. The criteria used for the validation of the analytical method applied to the cited matrices are the linear dynamic range of the response, the detection limit, the repeatability, the intermediate repeatability and the accuracy. A comparison with a method described in the literature for the bulk analysis of this antibiotic is made
Determination of enzyme kinetic constants for electrochemically mediated enzyme reactions. Application to the diaphorase–nicotinamide adenine dinucleotide system with p-methylaminophenolsulphate as an electrode carrier
No full textCyclic voltammetry was successfully applied to the study of the kinetics of the nicotinamide adenine dinucleotide (NADH)/diaphorase (DI)/p-methylamino-phenolsulfate (MAP) electrochemically mediated enzyme reaction. The voltammetric curves relative to the oxidation of MAP coupled with the enzymatic reaction were simulated by the DigiSim package without any simplifying assumption. The comparison between experimental and calculated curves allowed the determination of the rate constants involved in the various steps. In particular a value of 1.1×105 M−1 s−1 for the bimolecular rate constant for the reaction between enzyme and mediator and a value of 10 M−1 s−1 for the parallel competitive reaction between NADH and mediator were obtained. Other methods reported in the literature for studying the kinetics of enzymatic reactions were employed and the results were in perfect agreement with those obtained with the method based on digital simulation. A critical comparison of the merits of the different approaches is also reported
Kinetic study of the bioelectrocatalytic oxidation of NADH. The cyclic voltammetry-digital simulation approach.
No full textA general method for the electrochemical evaluation of the bimolecular rate constant in enzyme catalyzed reaction kinetics
No full textA general working curve in terms of the ratio of the kinetic limiting current of bioelectrocatalysis to the diffusion-controlled current recorded in the absence of the enzyme reaction versus the k[E] (k=bimolecular rate constant, [E]=enzyme concentration) group at high concentration of the substrate and at very low mediator concentration was constructed. The curve allows one to evaluate the bimolecular catalytic constant for one- or two-electron mediator from voltammetric data recorded at a fixed scan rate
Ossidazione elettrocatalitica del NADH tramite l'enzima diaforasi. Considerazioni sui metodi cinetici usualmente utilizzati
No full textA Study of the Reaction Kinetics of Electrogenerated Superoxide Ion with Benzylbromide
No full textThe decay kinetics of the unstable superoxide ion in the presence of a reactant is studied in aprotic mediu
Alcohol biosensor based on the immobilization of Meldola Blue and alcohol dehydrogenase into a carbon nanotube paste electrode
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