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== Week3 Tasks - Info For Nickel(II) cyclam perchlorate ==

(1.1, 1.3)Properties of Nickel (II) cyclam perchlorate

• Molecular formula: Ni(cyclam)(ClO₄)₂
• Molar Mass: 457.9 g/mol
• Melting Point: 140^oC
• Boiling Point:
• Solubility In Water: somewhat soluble

(1.2,1.4)Nickel(II) Cyclam Perchlorate

(1.5)Citations

• Mechanism of Nitrogen Fixation by Nitrogenase: The Next Stage
• Mechanism of Mo-Dependent Nitrogenase
• The Nitrogenase Regulatory Enzyme Dinitrogenase Reductase ADP-Ribosyltransferase (DraT) Is Activated by Direct Interaction with the Signal Transduction Protein GlnB

Reference

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(1.7) Table

Chemical Properties

opertyr e
Molar Mass (g/mol)	457.9
Melting point (oC)	140

(1.8) Formula

${\ce {(1/2)SO4^2- + 1/2Ba^2+ -> 1/2BaSO4}}$

(1.9) Chem Box

Nickel (II) Cyclam Perchlorate

Properties
Chemical formula	Ni(cyclam)(ClO4)2
Molar mass	457.9 g·mol
Melting point	140 °C (284 °F; 413 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Ferric Fe(III) and Ferrous Fe(II) Solubility

Using the conversion of ascorbate (Vitamin C) to monodehydroascorbate is essential when the ferric Fe(III) ion is converted to ferrous Fe(II).The Fe(III) species is insoluble, hence becoming one of the most problematic metal species to introduce and dissolve into an organisms system. Especially in eukaryotes such as humans, fungi, and bacteria, the upcycle of ascorbate is very important as well as the bioavailability of the ferrous (II) ion. There are three ways to increase the solubility of Iron (III) and overcome that challenge: chelation, reduction, and acidification.

Chelation

Chelation can increase the solubility of the iron (III) by coupling 'siderophore ligands' to the Iron species in its solid state to make it transform into an aqueous species. Especially in bacteria, and fungi, siderophores have a very strong binding affinity to Fe³⁺ and does not bind to other metal ions that may be present. The following is a general chemical equation to represent the process of chelation:

${\ce {Fe(OH)3 (s) + Siderophore -> [Fe(Siderophore)2]^3+ (aq) + 3OH^-}}$

A structure of an siderophore. The phenyls with two hydroxyl groups are the binding spots.

These iron complexes binds to a receptor on an iron transport that is unique to the siderophore used. The receptor dissociates once it nears the cell's membrane which creates an aqueous ferric Fe(III) ion that can either be used for uptake or reduced to Fe²⁺ where transporters specific to that ion can transport it instead.

Reduction

Reducing the ferrous (III) ion to ferrous (II) increases the bio availability which improves the rate and extent at which the aqueous soluble ferrous (II) iron will reach the system of the organism and will prevent the mineralization of the aqueous ferrous (III). The general for a following reduction in relation to an iron complex is as follows:

${\ce {Fe[Ligand]^3+ + e^- -> Fe[Ligand]^2+}}$

Once the iron complex nears the cell surface, the Iron (II) ion becomes susceptible to accept water ligands, thus hydrating the ion. This process usually occurs in aerobic environments where the Iron (II) ion is also favored. Once the complex is reduced, it must be then re-oxidized in proximity to the cell membrane because it contains binding sites typically only for Iron (III) ions that the protein will then undergo conformational changes to transition to the other side of the membrane.

There are some transporters that allow the Iron (II) ions to be transported directly such as the Fet4, Dmt1, and the Irt1, however these transporters aren't exactly selective as they provide difficulty in binding to the Iron (II) ion so other ions bind as well such as Zn(II), Mn(II), and Cd(II). Transportation like this mainly takes place in plants and in anaerobic environments where oxidation back to the Iron (III) species is impossible.

A mechanistic scheme of the conversion of ascorbate to monodehydroascorbate and ferric Fe(III) to ferrous Fe(II). The green shapes represent heme molecules that facilitate electron transfer in the overall mechanism.

`Contributions for Ferrireductase article (second 250 +400 words)

A generic heme molecule

Figure 2. Lysine, an amino acid used in the oxidated cytochrome b561.

Importance

Ascorbate, commonly known as Vitamin C, is a nutrient that is necessary for the function of the human body. Ascorbate also protects the body from the formation of free radicals and through antioxidants, protects the body from their harmful effects. The ferrireductase that depends on ascorbate concentrations is called cytochrome b561 found in eukaryotes. Cytochrome b561, as mentioned above, is a diheme cytochrome, which is a protein that contains two coordinating iron complexes (a heme) with porphyrin ligands coupled to it. Cytochrome b561, along with two special amino acids, Lysine⁸¹ (oxidized), and Histidine¹⁰⁶ (reduced), aid in catalyzing the electron transfer process and facilitate the conversion of ascorbate. A diagram is provided to show the general mechanistic scheme of the conversion of ascorbate to monodehydroascorbate. One molecule of ascorbate binds to the designation site involving Lys⁸¹ (on the cytoplasmic side of an oxidized cytochrome b561) and donates an electron, ultimately producing monodehydroascorbate and a proton. Reversely, monohydroascorbate will bind to His¹⁰⁶ (on the non-cytoplasmic side of reduced cytochrome b561) and accept both an electron and the proton previously generated, to regenerate another ascorbate to be used in the oxidized form again. In response to this mechanism, it facilitates the reduction of the ferric Fe (III) ion to the ferrous Fe(II) ion. A general reaction scheme of iron conversion in the plasma membrane is as follows:

Figure 3. Histidine, an amino acid used in the reduced cytochrome b651

${\ce {[Fe(L)6]^3+ (aq) + e- -> [Fe(OH2)6]^2+ (aq)}}$

The reduction of iron is crucial for the transport of iron through the cell membrane in human bodies since ferrous Fe (II) aqueous ions are more soluble and some transporters such as Ftr1 permease have high affinities for Fe²⁺.