Use of the confined spaces of apo-ferritin and virus capsids as nanoreactors for catalytic reactions

Abstract

Self-assembled protein cages providing nanosized internal spaces which are capable of encapsulating metal ions/complexes, enzymes/proteins have great potential for use as catalytic nanoreactors in efforts to mimic confined cellular environments for synthetic applications. Despite many uses in biomineralization, drug delivery, bio-imaging and so on, applications in catalysis are relatively rare. Because of their restricted size, protein cages are excellent candidates for use as vessels to exert control over reaction kinetics and product selectivity. Virus capsids with larger internal spaces can encapsulate multiple enzymes and can mimic natural enzymatic reactions. The apo-ferritin cage is known to accommodate various metal ions/complexes and suitable for organic transformation reactions in an aqueous medium. This review highlights the importance, prospects and recent significant research on catalytic reactions using the apo-ferritin cage and virus capsids.

A Photoactive Carbon‐Monoxide‐Releasing Protein Cage for Dose‐Regulated Delivery in Living Cells

“…[4][5][6][7] These composites,w hich have large numbers of metal compounds appropriately aligned on or within the scaffolds,s how ah igh reactivity when externally stimulated, for example,b yl ight irradiation. [8][9][10] Protein assemblies containing metal compounds are biocompatible and have been recently used for both in vitro and in vivo applications.…”

Conversion of the Native 24‐mer Ferritin Nanocage into Its Non‐Native 16‐mer Analogue by Insertion of Extra Amino Acid Residues

“…Reported approaches to designing self-assembling proteins have satisfied this requirement in different ways,s uch as the use of engineered disulfide bonds, [4,5] electrostatic interactions, [6] chemical cross-links, [7] metal-mediated interactions, [8] ligandinduced association, [9] computational interface design, [10,11] or genetic fusion of multiple protein domains or fragments. [21][22][23][24][25][26][27][28][29][30] Although these natural assemblies can be repurposed to perform new functions,t his strategy is limited to the structures of existing proteins,w hich may not be suited to agiven application. However,t he task of rendering SSIs controllable is complicated by the fact that SSIs are mediated by weak, noncovalent interactions over large surfaces.…”

“…However,t he task of rendering SSIs controllable is complicated by the fact that SSIs are mediated by weak, noncovalent interactions over large surfaces. [21][22][23][24][25][26][27][28][29][30] Although these natural assemblies can be repurposed to perform new functions,t his strategy is limited to the structures of existing proteins,w hich may not be suited to agiven application. [20] These protein cages have recently attracted considerable attention from researchers in the field of nanoscience and nanotechnology because they possess many useful properties such as high symmetry,s olubility and stability, monodispersity,a nd ease of genetic and chemical manipulation.…”

Biomineralization of a Cadmium Chloride Nanocrystal by a Designed Symmetrical Protein

“…[13] Partly based on such natural examples,m any groups are investigating the potential optical, magnetic,and electrical properties of novel protein-based materials for applications including memory devices, [14] biosensors, [15] and light-driven switches. [16] Other applications may include the creation of synthetic enzymes with inorganic or prosthetic catalytic groups, [17] and environmental bioremediation by adsorption of toxic elements. [18] Thestructure described here shows that metal ions are highly suitable ligands for controlling the oligomeric form of proteins with appropriately designed, symmetrical metalbinding sites,and that symmetrical proteins may likewise act as highly specific agents to order metal ions into crystal lattices.…”