A simple strategy to separate overlapping electron paramagnetic resonance (EPR) signals in biological systems is presented. Pulsed EPR methods (inversion- and saturation-recovery) allow the determination of the T(1) spin-lattice relaxation times of paramagnetic centers. T(1) may vary by several orders of magnitude depending on the species under investigation. These variations can be employed to...

A new approach to NMR solution structure refinement is introduced that uses paramagnetic effects on nuclear chemical shifts as constraints in energy minimization or molecular dynamics calculations. Chemical shift differences between oxidized and reduced forms of horse cytochrome c for more than 300 protons were used as constraints to refine the structure of the wild-type protein in solution and...

Fe3O4 nanostructures were synthesized via a facile hydrothermal reaction. The effect of various surfactants such as cationic and anionic on the morphology of the product was investigated. Magnetic nanoparticles were added to poly styrene for preparation of magnetic nanocomposite. Nanostructures were then characterized using X-ray diffraction, scanning electron microscopy and Fourier transform i...

In this work firstly Fe3O4 nanoparticles were synthesized via a sono-chemical method. At the second step magnesium hydroxide shell was synthesized on the magnetite-core under ultrasonic waves. For preparation Fe3O4-MgO the product was calcinated at 400 ºC for 2h. Properties of the product were examined by X-ray diffraction pattern (XRD), scanning electron microscope (SEM) and Fourier transform ...

In this research nickel zinc ferrite nanoparticles with composition of Ni1-xZnxFe2O4 (where x=0, 0.3, 0.7, 1) were synthesized by a sol-gel method at 600 °C for 5 hours. The structure of nanoparticles was studied using X-ray diffraction pattern. The lattice parameter of ferrite nanoparticles was calculated and indicates lattice constant of nanoparticl...

Ferredoxin from Azotobacter chroococcum has been studied by low-temperature magnetic-circular-dichroism and electron-paramagnetic-resonance spectroscopy. When aerobically isolated ferredoxin contains a [3Fe-4S] and [4Fe-4S] cluster. Anaerobic treatment with dithionite in the presence of ethanediol reduces the [3Fe-4S] cluster to give two spectroscopically distinct forms RI and RII which are rev...

The locus of inhibition of nicotinamide adenine dinucleotide, reduced form (NADH) oxidation in mitochondria by rotenone, piercidin A, and barbiturates is considered in the light of available information. Most lines of evidence indicate that the point of inhibition is on the O(2) side of NADH dehydrogenase. Kinetic experiments on the substrate-induced appearance of the electron paramagnetic reso...

The sensitivity of nicotinamide adenine dinucleotide (NADH) oxidase and succinoxidase to metal chelators, the generation of an electron paramagnetic resonance (EPR) signal upon addition of these substrates, and the rate of formation of the EPR signal relative to the rate of the cytochrome reduction suggest the participation of nonheme iron proteins in the respiratory process of Escherichia coli...

Reaction of the nitrosylated-iron metallodithiolate ligand, paramagnetic (NO)Fe(N 2 S ), with [M(CH 3 CN) n ][BF 4 ] salts (M = Ni II , Pd and Pt ; or 6) affords di-radical tri-metallic complexes in a stairstep type arrangement ( [FeMFe] 2+ M...