Ferritin protein cage

A second metallic contaminant of interest is Cr. Remediation of Cr-contaminated soils is centered around the reduction of Cr(VI), a more toxic and soluble form, to Cr(III), which is considerably less soluble and which readily precipitates out of solution. A number of different nanoparticles have been shown to possess this capability, including ferritin protein cages containing fenihydrite (Fe(O)OH), palladium (Pd) nanoparticles, and carboxymethyl cellulose (CMC)-stabilized Fe ) (87, 89, 93). In both the ferritin cages and the CMC-Fe p), the active species was a form of Fe, either Fe(0) in the case of the CMC-Fe p), or Fe(II) in the case of the ferritin cages. The reaction known to reduce Cr(VI) utilizing Fe(II) is shown in Equation (20.2). 

Ferritin protein cage [38] Boiling aqueous solution by refluxing the ferritin protein cage/ferrihydrite composite... 

Traditional methods for fabricating nano-scaled arrays are usually based on lithographic techniques. Alternative new approaches rely on the use of self-organizing templates. Due to their intrinsic ability to adopt complex and flexible conformations, proteins have been used to control the size and shape, and also to form ordered two-dimensional arrays of nanopartides. The following examples focus on the use of helical protein templates, such as gelatin and collagen, and protein cages such as ferritin-based molecules. 

To understand the molecnlar mechanism of biomineralization, it is very important to study the initial metal binding process as well as the process of metal clnster formation. However, little is known so far on the interactions between amino acids and metal clusters. Ferritin and other ferritin-like spherical proteins are known to catalyze biomineralization in the protein cages [4,49]. For example, Fe" ions incorporated in these protein cages are oxidized to Fe " at the ferroxidase center and deposited in the protein large cavities as iron oxides [49]. 

Metal Oxide Synthesis within a Protein Cage-Ferritin... 

The defined architecture of the metalloprotein ferritin, a natural complex of iron oxide, is found in almost all domains of life and has been used as a constrained reaction vessel for the synthesis of a number of non-natural metal oxides [28, 34]. The protein ferritin consists of 24 subunits that self-assemble into a cage, consisting of a threefold hydrophilic channel coordinated to a fourfold hydrophobic channel [20, 28]. In biology, Fe(ll) is introduced into the core of the apoprotein through its hydrophiUc charmels where the ferrous ion is catalytically oxidized to a less-soluble ferric ion, Fe(lll) [20]. The ferric ion then undergoes a series of hydrolytic polymerizations to form the insoluble ferric oxyhydroxide mineral (ferrihydrite), which is physically constrained by the size of the protein cage (12 nm outer diameter, 8nm inner diameter) [35]. The enzyme ferrous oxidase is coordinated within the protein cage, the interior and exterior of which is electrostatically dissimilar, to produce spatially defined minerals. 

The studies of high-nuclearity iron cages were originally motivated by a desire to understand biomineralization processes and the form of iron found in the iron-storage protein ferritin. Therefore, many of the... 

Fenton reaction reaction of iron with hydrogen peroxide to form hydroxyl radicals, fermentation form of anaerobic (oxygen-free) respiration used by yeasts, which produces ethanol as an end-product, ferritin cage-like protein that locks away iron within cells. 

Accumulation of Metals in a Protein Assembly Cage of Ferritin... 

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