Folding-Refolding of Ferritin as Template in Design of Nanoclusters of Copper and Manganese Oxides

Abstract

Bio-templates such as proteins, lipids offer rich structural and functional diversity for the synthesis of nanoparticles by controlling their shape, size and orientation. In this work we have exploited a pH dependent folding-refolding feature of Horse Spleen Apoferritin (HsAFr) to synthesize copper and manganese oxide nanoparticles in a controlled manner. Two methods of preparation were used in this study. In the first method, Copper Sulphate (100 mM) and Manganese Chloride (4.8 mM) have been incubated with the protein and the pH dynamically adjusted for homogeneous incorporation of the metal ions into the HsAFr shell. The second study involved the incorporation of Cu2+ and Mn2+ inside HsAFr cavity and subsequent designing of nanoclusters of the respective oxides. UV, fluorescence and far-UV circular dichroism (far-UV CD) spectroscopic techniques have been used to study the mineralization effect of the metal inside the HsAFr cavity. Size determination carried out using XRD suggested an average size ranging from 20-30 nm. The EPR of the nanoclusters show that incorporation of Mn2+ leads to a characteristic magnetoferritin behavior.

Heavy metal detoxification by recombinant ferritin from Apostichopus japonicus

“…Circular dichroism is a spectroscopic technique that is broadly used for assessing macromolecular interactions and conformational changes in solution. 65,66 In this study, we determined the secondary structure of ferritin aer refolding, using standard HSF as a comparison sample. The results suggest that activated AjFER can be obtained using a stepwise decrease of urea.…”

“…This inconsistency may be attributed to the properties and binding sites of Pb 2+ , as changes in the microenvironment near binding sites promote b-sheet formation. Harshith Subramanian et al 66 investigated the effect of Cu 2+ and Mn 2+ on horse spleen apoferritin, revealing that the number of b-sheets changed in response to treatments with different metal ion species and at different concentrations. We readily admit that only a secondary structure measurement, as found here, may not fully reect the binding mechanism of metal ions and protein.…”

Multifaceted Applications of Ferritin Nanocages in Delivering Metal Ions, Bioactive Compounds, and Enzymes: A Comprehensive Review

“…92 Furthermore, this structure permits Cu 2+ to bind to the 3-fold channel of apoferritin, resulting in a stable thiol bridge structure reinforced by His and Glu. 93 This promising research paves the way for the creation of enhanced copper supplements based on this chemical transformation process. 3.5.…”

“…Moreover, the intrinsic process allows for the production of size-limited metal nanoparticles within the protein’s core through a reduction facilitated by NaBH 4 . Furthermore, this structure permits Cu 2+ to bind to the 3-fold channel of apoferritin, resulting in a stable thiol bridge structure reinforced by His and Glu . This promising research paves the way for the creation of enhanced copper supplements based on this chemical transformation process.…”