A kinetic and mechanistic study of oxidation of L-lysine by diperiodatonickelate(IV) in aqueous alkaline medium

1470-1475The kinetics of oxidation of L-lysine by diperiodatonickelate(IV) (DPN) in aqueous alkaline medium at a constant ionic strength of 0.60 mol dm-3 has been studied spectrophotometrically. The reaction shows first order in diperiodatonickelate(IV) and less than unit order dependence each in lysine and OH- ion concentrations. The addition of periodate retards the reaction, while the product nickel(II) do not show any significant effect on the reaction rate. An increase in ionic strength and decrease in dielectric constant of the medium decreases the rate. A mechanism based on experimental results is proposed. The constants involved in the mechanism are evaluated. The activation parameters with respect to slow step of the mechanism are computed and discussed

Impact of Bacterial Inoculums, Organic Residues and Mineral Fertilization Levels on Growth Traits of Dry Direct Seeded Rice Grown under Aerobic Conditions

A field experiment was conducted at Agricultural Research Station, Gangavathi, University of Agricultural Sciences, Raichur, Karnataka during kharif seasons for two consecutive years (2019 and 2020) to study the influence of zinc and iron biofortification on physiological parameters of dry direct seeded rice under aerobic condition. The experiment was laid out in split plot design and comprised of two factors for the study viz., main plots and sub plot treatments. Perusal of pooled data of two years showed that, among the rice genotypes, G3: GNV-10-89 recorded significantly higher dry matter production accounted for 23.75, 69.92 and 82.73 g hill-1 at 60, 90 DAS and at harvest, respectively, leaf area 512.09, 543.92 and 376.57 cm2 hill-1, leaf area duration 45.60, 79.05 and 68.92 days and crop growth rate 34.78, 76.95 and 21.34 g cm-2 day-1 for the same sequences as compared to other genotype. With respect to micronutrient application, M6: Soil application of ZnSO4 @ 15 kg ha-1 and FeSO4 @ 10 kg ha-1 + foliar application of ZnSO4 @ 0.5 % and FeSO4 @ 0.5 % at 30 and 45 DAS recorded significantly higher dry matter production (27.26, 80.88 and 93.22 g hill-1 at 60, 90 DAS and at harvest, respectively), leaf area (514.21, 542.65 and 382.68 cm2 hill-1 at 60, 90 DAS and at harvest, respectively), leaf area duration (46.27, 79.20 and 69.22 days during 30-60 DAS, 61-90 DAS and 91 DAS-at harvest, respectively) and crop growth rate (39.10, 89.37 and 20.56 g cm-2 day-1 at 30-60 DAS, at 61-90 DAS and at 91 DAS-at harvest, respectively) as compared to other micronutrient application. The observed trends during 2019 and 2020 were nearly closed to each other

Non-covalent binding analysis of sulfamethoxazole to human serum albumin: Fluorescence spectroscopy, UVâvis, FT-IR, voltammetric and molecular modeling

This study was designed to examine the interaction of sulfamethoxazole (SMZ) with human serum albumin(HSA). Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of human serum albumin by SMZ was static mechanism. The binding constant values for the SMZâHSA system were obtained to be 22,500 L/mol at 288 K, 15,600 L/mol at 298 K, and 8500 L/mol at 308 K. The distance r between donor and acceptor was evaluated according to the theory of Föster energy transfer. The results of spectroscopic analysis and molecular modeling techniques showed that the conformation of human serum albumin had been changed in the presence of SMZ. The thermodynamic parameters, namely enthalpy change (âH0) â36.0 kJ/mol, entropy change (âS0) â41.3 J/mol K and free energy change (âG0) â23.7 kJ/mol, were calculated by using van׳t Hoff equation. The effect of common ions on the binding of SMZ to HSA was tested. Keywords: Human serum albumin, Sulfamethoxazole, Fluorescence quenching study, Static mechanis

Oxidation of glycine by diperiodatocuprate(III) in aqueous alkaline medium

200-206Oxidation of the amino acid, glycine, by diperiodatocuprate(III) is studied spectrophotometrically in alkaline medium at constant ionic strength (0.20 mol dm-3) and at varying temperatures (298-318 K). The reaction between diperiodatocuprate(III) and glycine in aqueous alkaline medium exhibits 1:4 stoichiometry. Intervention of free radicals is observed in the reaction. Mechanism involving monoperiodatocuprate(III) as the reactive oxidant species, proceeding through the formation of a complex is proposed. The reaction constants involved in the different steps of the mechanism and activation parameters with respect to the slow step of the mechanism are computed and discussed. The thermodynamic quantities are also determined for the various equilibrium steps. The isokinetic temperature is found to be 381 K

KINETICS AND MECHANISM OF OXIDATION OF AN ANTIARRHYTHMIC DRUG PROCAINAMIDE HYDROCHLORIDE BY MN (VII) IN AQUEOUS SULPHURIC ACID MEDIUM: A STOPPED FLOW TECHNIQUE

Objective: To understand the kinetics and mechanism of oxidation of procainamide hydrochloride by Mn(VII) in aqueous sulfuric acid medium at 298K and at constant ionic strength, I= 3.0×10-3 mol dm-3 and to identify its oxidation products.Methods: Kinetic measurements were performed on a Varian CARRY 50 Bio UV- visible spectrophotometer connected to a rapid kinetic accessory (HI-TECHSFA-12 unit). The products are characterized by FT-IR, GC-MS and NMR studies.Results: The reaction stoichiometry was determined and the results indicate that five moles of procainamide require four moles of Mn(VII). The oxidation products were identified as Mn(II), p-aminobenzoic acid and N,N-diethyl-2-nitrasoethanamine. The reaction shows first-order kinetics with respect to MnO4-and fractional order with respect to procainamide. Increase in sulphuric acid concentration increased the rate of reaction with fractional order dependence on H+ion concentration. The effect of added products, ionic strength, and dielectric constant of the medium were studied on the rate of reaction.Conclusion: A suitable mechanism is proposed on the basis of experimental results. The activation parameters with respect to the slow step of the mechanism were evaluated and the thermodynamic parameters are also determined and discussed.Â

Binding of fexofenadine hydrochloride to bovine serum albumin: structural considerations by spectroscopic techniques and molecular docking

<p>The binding interaction of peripheral H₁ receptor antagonist drug, fexofenadine hydrochloride to bovine serum albumin (BSA) is investigated by fluorescence spectroscopy in combination with UV-absorption spectroscopy under physiological conditions. The Stern–Volmer plots at different temperatures and the steady state fluorescence suggested a static type of interaction between fexofenadine and BSA. Binding constants were determined to provide a measure of the binding affinity between fexofenadine and BSA. It was found that BSA has one binding site for fexofenadine. On the basis of the competitive site marker experiments and thermodynamic results, it was considered that fexofenadine was primarily bound to the site I of BSA mainly by hydrogen bond and van der Waals force. Utilising Förster resonance energy transfer the distance, <i>r</i> between the donor, BSA and acceptor fexofenadine was obtained. Furthermore, the results of circular dichroism and synchronous fluorescence spectrum indicated that the secondary structure of BSA was changed in the presence of fexofenadine. Molecular docking was applied to further define the interaction of fexofenadine with BSA.</p

Multi-spectroscopic investigation of the binding interaction of fosfomycin with bovine serum albumin

The interaction between fosfomycin (FOS) and bovine serum albumin (BSA) has been investigated effectively by multi-spectroscopic techniques under physiological pH 7.4. FOS quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites n and observed binding constant KA were measured by the fluorescence quenching method. The thermodynamic parameters ÎG0, ÎH0 and ÎS0 were calculated at different temperatures according to the vanât Hoff equation. The site of binding of FOS in the protein was proposed to be Sudlowâs site I based on displacement experiments using site markers viz. warfarin, ibuprofen and digitoxin. The distance r between the donor (BSA) and acceptor (FOS) molecules was obtained according to the Förster theory. The effect of FOS on the conformation of BSA was analyzed using synchronous fluorescence spectra (SFS), circular dichroism (CD) and 3D fluorescence spectra. A molecular modeling study further confirmed the binding mode obtained by the experimental studies. Keywords: Fosfomycin, Serum albumin, Spectroscopic methods, Synchronous fluorescence, 3D spectr