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  1. Free, publicly-accessible full text available July 20, 2024
  2. Magnetic micelles with surface decorated by S-rich chelates sequester ototoxic cisplatin in aqueous solutions, and the isolation of cisplatin-saturated micelles is steered by external magnets.

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    Free, publicly-accessible full text available July 25, 2024
  3. Supercharged proteins exhibit high solubility and other desirable properties, but no engineered superpositively charged enzymes have previously been made. Superpositively charged variants of proteins such as green fluorescent protein have been efficiently encapsulated within Archaeoglobus fulgidus thermophilic ferritin (AfFtn). Encapsulation by supramolecular ferritin can yield systems with a variety of sequestered cargo. To advance applications in enzymology and green chemistry, we sought a general method for supercharging an enzyme that retains activity and is compatible with AfFtn encapsulation. The zinc metalloenzyme human carbonic anhydrase II (hCAII) is an attractive encapsulation target based on its hydrolytic activity and physiologic conversion of carbon dioxide to bicarbonate. A computationally designed variant of hCAII contains positively charged residues substituted at 19 sites on the protein’s surface, resulting in a shift of the putative net charge from −1 to +21. This designed hCAII(+21) exhibits encapsulation within AfFtn without the need for fusion partners or additional reagents. The hCAII(+21) variant retains esterase activity comparable to the wild type and spontaneously templates the assembly of AfFtn 24mers around itself. The AfFtn–hCAII(+21) host–guest complex exhibits both greater activity and thermal stability when compared to hCAII(+21). Upon immobilization on a solid support, AfFtn–hCAII(+21) retains enzymatic activity and exhibits an enhancement of activity at elevated temperatures. 
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  4. Abstract

    We characterize the encapsulation of supercharged green fluorescent protein, GFP(+36), by thermophilic ferritin fromArchaeoglobus fulgidus(AfFtn). The AfFtn–GFP(+36) assembly is rapid, nearly stoichiometric, and robust. Using a more stably assembled mutant AfFtn, we show that encapsulation can occur in the presence of mostly assembled cages, in addition to encapsulation starting from AfFtn individual subunits. Assembly and encapsulation do not occur with non‐supercharged GFP or the alternately supercharged GFP(−30), highlighting the role of complementary electrostatic interactions between the cargo and AfFtn cage interior. We also present a method for verifying protein–protein encapsulation, using nickel nitrilotriacetic acid agarose resin. AfFtn‐supercharged protein host‐guest complexes could find applications in enzyme studies, protein separations, andin vivoprotein stabilization and targeted delivery.

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  5. Abstract

    The ferritin family of proteins can be thought of as natural, nano‐sized containers. Their native function is to oxidize and store iron as a hydrated ferric oxide mineral, which can be removed to give apoferritin. The hollow interior (D=5–8 nm) provides an excellent template for inorganic nanoparticle (NP) synthesis. In addition to preparing new coresin situ, apoferritins can be disassembled and reassembled around a NP of interest. Ferritin encapsulation increases NP biocompatibility and allows site‐specific functionalization. We and others have prepared many NP‐filled ferritins, as well as ferritins loaded with small molecules of interest. Uniquely, apoferritin serves as a model for a general anesthetic‐protein binding site, which has led to the discovery of the first fluorescent general anesthetic and improved understanding of anesthetic mechanisms. Finally, ferritin conjugates have exciting applications for targeted delivery, which we have explored in the vascular endothelium.

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