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Fruit batteries and saltwater batteries are excellent ways to explore simple circuits in the classroom. These are examples of air batteries in which metal reacts with oxygen in the air in order to generate free electrons, which flow through an external circuit and do work. Students are typically told that the salt or fruit water acts as an electrolyte to bring electrons from the anode to the cathode. That's true, but it leaves the battery as a black box. Physics teachers often don't have the background to explain the chemistry behind these batteries. We've written this paper to explore the electrochemistry behind an air battery using copper cathode, aluminum anode, and saltwater.

The thermodynamic study of Fe(super 2+) binding to EcFtnA and its variants is presented to determine the location of the primary ferrous ion-binding sites on the protein and to better understand the role of the third C site in iron binding. The result reveals that isothermal titration calorimetric analyses of the wild type protein states the presence of two main classes of binding sites in the pH range ascribed to Fe(Super 2+) binding.

Results demonstrate that the iron entry to the interior of the human H-chain ferritin shell occurs through the 3-fold channels. The principal iron binding site is at the ferroxidase center and mutations of the Asp and Glu residues of the 3-fold channels reduce the amount of iron accessing the ferroxidase centers.

Research has been conducted on the ferritins, the iron storage and detoxification proteins. The use of sensitive fluorescence assay and based on O (sub)2 evolution assay in demonstrating that hydrogen peroxide is produced in horse spleen ferritin ia discussed.

Research describes the syntheses of an array of N-substituted-tach-Cu(II)-dihalide complexes and the cognate tach ligands together with their solid-state and solution structure. Results discuss the Cu(II) complexes of N,N',N'-trialkyltach derivatives of cis,cis-1,3,5-triaminocyclohexane.

Electron paramagnetic resonance spectroscopic analysis indicates that the dicopper complex is formed only if bis(p-nitrophenyl) phosphate (BNPP) is present. The hydrolysis of activated phosphate diesters, such as BNPP, by dicopper complexes and the mechanism of action are discussed.

Research has been conducted on the bacterioferritins. Iron oxidation and hydrolysis chemistry in Escherichia coli bacterioferritin carried out by means of electrode oximetry/pH are discussed.

Research has been conducted on the iron-binding properties of the N-lobe following ligand mutations. The changes resulting from mutating His 249 are discussed.

Research was conducted to examine the reaction paths of iron oxidation and hydrolysis in horse spleen and recombinant human ferritins using electrode oximetry. The oxygen electrode response was examined and tested on model reactions confirming previous findings that electrode oximetry accurately measures the steady-state oxygen uptake kinetics of ferritin. Results further suggest that naturally occurring heteropolymeric ferritins display enzymatic behavior.

The significance of tyrosine ligands in transferrin was investigated through using different techniques including high-resolution electroparamagnetic resonance spectra. Results revealed that inequivalence of the two tyrosine ligands in iron and copper binding with transferrins was opposite rendering the coordination geometry and charge of the metal ion critical for metal interaction with transferrin. Tyrosine 188 ligand mediated the normal binding of the protein with iron.

The oxidative deposition of iron in ferritin leads to the formation of a tyrosyl radical. The difference in the spectra of mixed H/L chain horse spleen ferritin (HoSF) and H-chain recombinant human ferritin (HuHF) illustrates the presence of more than one pathway for the radical production. The H-chain HuHF tyrosyl radical seems to arise from the oxidation of Fe2+. The L-chain-rich HoSF radicals formed from hydroxyl radical damage to the protein are centered on aromatic acids and probably arise from histidine.

Rapid-mixing freeze-quench techniques and EPR spectroscopic studies of EPR-active species formed during oxidative deposition of iron in horse spleen apoferritin reveal that iron(II) oxidation primarily yields a monomeric Fe3+-protein complex as an EPR-active intermediate. A mixed-valent Fe2+-Fe3+ complex and a new radical with axial symmetry are the other EPR-active species formed at slower rates during the reaction. The mixed valent species is the direct product of the Fe3+-protein complex, while the temporary radical is associated with an Fe2+ center.

Nitric oxide and non-heme ion-protein interactions are detected by specifying the nitric oxide structures and their EPR properties in mammalian ferritin. Three EPR signals are seen in the iron-nitrosyl complexes. The iron-nitrosyl complex development is influenced by the His-128 and Cys-130 residues near the 3-fold channels.

The region between the Fe(II) state and an activated Fe(III) state allow reversible cycling of the non-heme iron center of 5-lipoxygenase. Stoichiometry with certain properties are displayed by titrations of 5-lipoxygenase with the 13-(S)-hydroperoxy-9-cis-11-trans-octadecadienoic acid, 13-HPOD. The Fe(II) state is reached by the Fe(III) of the 13-HPOD-activated enzyme when a reducing agent N-(chlorophenyl)-N-hydroxy-N'-(3-chlorophenyl)urea, CPHU, is introduced. CPHU and other reducing agents attenuate 5-lipoxygenase by their ability to eliminate enzyme-catalyzed 13-HPOD.

The kinetic characteristics of ferritins are discussed. The H-subunit exhibits catalytic activity and is controlled by the occurrence of the L-subunit. The core develops at a speed similar to the kinetics of the iron (II) oxidation in mutants. A dimeric iron specimen can be developed at the ferroxidase center due to the kinetics of both rHF and HLF. A solitary dioxygen molecule participates in the two one-electron-transfer steps through which the oxidation of iron (II) takes place.

Significance of three of the four residues comprising of a loop in the N-lobe (Pro142, Lys144, and Pro145) for the high-affinity interaction of human serum transferrin (hTF) with the transferrin receptor (TFR) is described. The data demonstrated the critical role of Arg143 as a kinetically significant anion binding (KISAB) site that is sensitive to salt concentration and to the conformational change necessary to induce iron release from the N-lobe of hTF (in the absence of the TFR).

The UV-vis and EPR spectroscopy approach is employed to explain the various structural and functional effects of the substitution of glycine 65 with arginine in the N-lobe of human transferrin. The hydrogen bond is shown to play an extremely significant role in the flexibility of the N-lobe of the system.

Ultraviolet/visible and fluorescence stopped-flow spectrophotometries are used for determining the kinetics and pathways of [Fe.sup.2+] diffusion into the protein shell, its binding at the ferroxidase center and its subsequent oxidant by [O.sub.2]. Y34W variants of human H-chain ferritin have provided new insights into the very early events of iron deposition in ferritin.

The ability of human H-chain ferritin (HuHF) to attenuate hydroxyl radical production by the Fenton reaction is examined by electron paramagnetic resonance (EPR) spin-trapping methods. The observed .OH radical has come from the reaction of H2O2 with either the mu-oxo diFe(III) complex at the ferroxidase site or the newly formed Fe(III) core.

The characterization of the primary structure of the extrapallial (EP) protein by RT-CPR and cDNA sequency methods and by de novo peptide sequency with mass spectrometry is reported. It is observed that the EP protein is multi-functional like it acts as a Ca2 transport protein, a shell matrix protein and a heavy metal detoxification protein.

The role of the ferroxidase center in iron uptake and hydrogen peroxide detoxification is investigated in Listeria innocua DNA binding protein from starved cells (LiDps). It is concluded that the behavior of the ferroxidase center variants of LiDps show that an intact ferroxidase center is not required when the bacterium is in an aerobic environment.

The chemistry of iron binding and oxidation in Listeria innocua DNA binding protein from starved cells (LiDps) is studied using H(sub 2)O(sub 2) as oxidant to further define the mechanism of iron deposition inside the protein and the role of LiDps in protecting DNA from oxidative damage. It is concluded that the reactions occur in place of undesirable odd-electron redox processes that produce hydroxyl radical.

The kinetics of iron uptake by recombinant human H-chain ferritin under conditions of variable iron loading of the protein is examined by employing multiwavelength stopped-flow spectrophotometry. A catalytic model for mineralization that accounts for the unusual features of the observed kinetics is also presented.

The studies of nucleation site variant A2 (E61A/E64A/E67A) of H-chain ferritin have shown impaired iron oxidation activity and mineralization, which may be due to disruption of the ferroxidase site of the protein. A new nucleation site variant A1 (E64A/E67A), which retains the ferroxidase site ligand Glu61, is employed to demonstrate that the putative 'nucleation site' does not play an important role in iron uptake or mineralization in H-chain ferritin.