Oxidation of deoxy myoglobin by [Fe(CN)6]3-.

The ability of myoglobin (Mb) to reversibly bind O2 and other ligands has been well characterized. Mb also participates with a variety of redox metals to form metmyoglobin (metMb). By using an anaerobic stopped-flow device we have measured outer-sphere oxidation by [Fe(CN)6]3 of native sperm whale myoglobin, recombinant wild-type Mb, and a series of mutant Mb proteins in which the distal His-64 was changed to Gly, Phe, Leu or Val.

Neuroelectric assessment of nutrient intake.

Electroencephalographic (EEG) activity and auditory event-related brain potentials (ERPs) were assessed in two groups (n = 12 each) of subjects. The 'food-nutrient' group had fasted from the night before and consumed a 500 cal nutrient drink; the 'control' group consumed breakfast but did not consume any nutrients during the recordings. All subjects were assessed every 15 min for six trial blocks at the same time of day, with the fast/nutrient group measured initially before and after consuming the nutrient drink.

Copper-specific damage in human erythrocytes exposed to oxidative stress.

Ascorbate and complexes of Cu(II) and Fe(III) are capable of generating significant levels of oxygen free radicals. Exposure of erythrocytes to such oxidative stress leads to increased levels of methemoglobin and extensive changes in cell morphology. Cu(II) per mole is much more effective than Fe(III).

Hemoglobin: a mechanism for the generation of hydroxyl radicals.

Oxyhemoglobin (HbO2) reduces Fe(III)NTA aerobically to become methemoglobin (metHb) and Fe(II)NTA. These conditions are favorable for the generation via Fenton chemistry of the hydroxyl radical that was measured by HPLC using salicylate as a probe. The levels of hydroxyl radicals generated are a function of both the percent metHb formed and the chemical nature of the buffer.

The science of nutrition - the metaphysics of food.

With respect for the differences between and among nations, there are universal principles on which public health nutrition policy should be based. An adequate food supply containing sufficient energy and all of the essential nutrients should be available and affordable. This may include nutrient-restored or fortified food products and supplements.

Low-level oxidative stress causes cell-cycle specific arrest in cultured cells.

Oxidative stress is involved in a multitude of pathological conditions. In the present study, cell cycle arrest was demonstrated in monolayer cultures of Chinese hamster ovary cells subjected to low-level oxidative stress induced by the addition of hydrogen peroxide. Fluorescence-activated cell sorting analysis characterized this arrest as occurring in both the G1 and G2/M phases of the cell cycle.

Sites and mechanisms of low-level oxidative stress in cultured cells.

Oxidative stress is involved in a multitude of pathological conditions. In the present study, we investigated the cellular targets and the mechanisms of low-level oxidative stress in a Chinese Hamster Ovary cell culture. Oxidative stress was induced either by continuous enzymatic production of superoxide or by bolus addition of hydrogen peroxide (H2O2).

Zinc(II) and copper(II) binding to serum albumin. A comparative study of dog, bovine, and human albumin.

Metal binding strategies employing low molecular weight chelators and equilibrium dialysis were used to investigate several unresolved aspects of zinc and copper binding to serum albumin. Direct measurement of histidine binding to bovine serum albumin when the histidine is presented either as a metal-chelate or alone provides no evidence for an albumin-metal-histidine ternary complex. Using previously determined intrinsic constants for Zn(II) and Cu(II), we have measured zinc binding to bovine serum albumin in the presence of saturating amounts of copper.

Spinal bone loss in postmenopausal women supplemented with calcium and trace minerals.

The effects of calcium supplementation (as calcium citrate malate, 1000 mg elemental Ca/d) with and without the addition of zinc (15.0 mg/d), manganese (5.0 mg/d) and copper (2.

Intrinsic stoichiometric equilibrium constants for the binding of zinc(II) and copper(II) to the high affinity site of serum albumin.

Intrinsic stoichiometric equilibrium constants were determined for zinc(II) and copper(II) binding to bovine and human serum albumin. Data were obtained from equilibrium dialysis experiments. Metals were presented to apoprotein as metal chelates in order to avoid metal hydrolysis and to minimize nonspecific metal-protein interactions.

Thiols, gold-thiols, zinc-thiols and the redox state of hemoglobin.

The beta subunit of human hemoglobin can be oxidized site-specifically through beta-Cys-93 by Cu(II)(His)2. A series of thiol ligands, gold thiols and zinc(II) inhibit this oxidation. The thiol inhibitors formed a transient ternary intermediate involving Cu(I) with consequent inhibition of electron transfer from the Fe(II)-heme.

The role of trace minerals in osteoporosis.

Osteoporosis is a multifactorial disease with dimensions of genetics, endocrine function, exercise and nutritional considerations. Of particular considerations are calcium (Ca) status, Vitamin D, fluoride, magnesium and other trace elements. Several trace elements, particularly copper (Cu), manganese (Mn) and zinc (Zn), are essential in bone metabolism as cofactors for specific enzymes.

Site-directed mutagenesis of histidine residues involved in Cu(II) binding and reduction by sperm whale myoglobin.

Sperm whale myoglobin (Mb) reduces Cu(II) through a site-specific mechanism involving complexation by one or more surface histidine residues. Three mutants of Mb, derived from recombinant wild-type Mb, were designed in which surface histidine residues exhibiting strong Cu(II) binding were replaced with amino acids with comparatively poor metal binding characteristics. The kinetics of Cu(II)(Gly)2 reduction by native Mb, recombinant wild-type Mb, and the mutants were compared.

Metal-ion-directed site-specificity of hydroxyl radical detection.

A wide variety of .OH detectors are in use for determination of biological .OH production.

Spinal bone density and calcium intake in healthy postmenopausal women.

Dietary calcium intake and bone mineral density (BMD) of the lumbar spine (L2-L4) were determined in 131 healthy free-living postmenopausal women (aged 64.7 +/- 7.6 y, means +/- SD).

Kinetics and mechanisms of reduction of Cu(II) and Fe(III) complexes by soybean leghemoglobin alpha.

The reduction of low-molecular-weight Cu(II) and Fe(III) complexes by soybean leghemoglobin alpha was characterized using both kinetic analysis and 1H-NMR experiments. Whereas Fe(III) (CN)6(3-) was reduced through an outer sphere transfer over the exposed heme edge, all other Cu(II) and Fe(III) complexes investigated were reduced via a site-specific binding of the metal to the protein. Reduction of all metal complexes was enhanced by decreasing pH while only Fe(III)NTA reduction kinetics were altered by changes in ionic strength.

Cardiac reperfusion damage prevented by a nitroxide free radical.

Experimental evidence is presented that directly links ischemia/reperfusion injury to the formation of oxygen-derived free radicals. 2,2,6,6-Tetramethylpiperidine-N-oxyl (TEMPO)--a stable nitroxide radical that disproportionates superoxide radicals and oxidizes reduced metal ions required for OH. formation--was tested for its ability to prevent reperfusion damage in the isolated rat heart subjected to regional ischemia.

Different cellular targets for Cu- and Fe-catalyzed oxidation observed using a Cu-compatible thiobarbituric acid assay.

The widely used thiobarbituric acid (TBA) assay for oxidative damage to biomolecules fails in Cu2(+)-containing solutions due to the formation of a cloudy precipitate. The chelation of Cu2+ ions with EDTA or Chelex was investigated. Both prevented precipitate formation, but only Chelex allowed proper color development in the TBA assay.

Long-term estrogen replacement therapy in postmenopausal women sustains vertebral bone mineral density.

The cross-sectional relationship between long-term estrogen use and vertebral (L2-4) bone mineral density (BMD) was determined in 65 postmenopausal white women between 55 and 75 years who were at least 10 years from their menopause. Long-term estrogen users began therapy within 5 years of menopause and continued for a duration of at least 10 years. The mean duration of use was 19.

Time-dependent modifications of ferric-adriamycin.

The biological and chemical properties of the ferric-Adriamycin complex changed with time after its preparation. Our experiments demonstrated that the toxicity of the iron-chelate in mice decreased as a function of its age. The reduced toxicity can be correlated with changes in the difference spectrum of ferric-Adriamycin vs Adriamycin (ADR), where a peak around 610 nm shifted to the 570 nm region.

The effect of zinc on reperfusion arrhythmias in the isolated perfused rat heart.

Considerable evidence suggests that free radicals engendered by redox-active metals, particularly iron and copper, are causative agents in reperfusion injury following ischemia. This study demonstrates that perfusion of the isolated rat heart with a buffer containing zinc, a non-redox active metal similar to copper in its coordination chemistry, inhibits the development of ventricular arrhythmias during reperfusion. Zinc was employed as the bishistidine complex, Zn--His2, to maintain solubility and permeability.

Zinc--a redox-inactive metal provides a novel approach for protection against metal-mediated free radical induced injury: study of paraquat toxicity in E. coli.

The essential mediatory role of copper and iron in a variety of free radical-induced injuries, including paraquat-induced biological damage has been recently demonstrated. It was postulated that these transition metals undergo cyclic redox reactions, and serve as centers for repeated production of hydroxyl radical, which are the ultimate deleterious agents. Additionally, we had presented evidence indicating efficient protection against paraquat toxicity by agents commonly employed (chelators, chemical scavengers and protecting enzymes).