Influence of Organic Structure Directing Agent Isomer Distribution on the Synthesis of SSZ-39

The aluminosilicate molecular sieve with the AEI framework topology (SSZ-39) is currently of great interest for use in a number of important applications such as exhaust gas NO_x reduction and the methanol-to-olefins reaction. It is likely that advances in the synthesis of this molecular sieve will be needed for applications to proceed. Here, dimethylpiperidine based organic structure directing agents (OSDAs) are used to prepare SSZ-39, and the influence of diastereo- and structural isomeric mixtures on the synthesis of SSZ-39 is reported. Although differences in the rates of molecular sieve formation as well as preferential isomer incorporation occur, the synthesis of SSZ-39 is possible over a wide range of isomeric mixtures. These findings demonstrate that the synthesis of SSZ-39 can be accomplished with OSDA isomer mixtures that naturally occur from the synthesis of the organic precursors used to prepare the OSDAs

Engineered metal-binding proteins: purification to protein folding

Proteins can make use of metal ions to bind substrates, to maintain structure, to effect catalysis, and for allosteric control and regulation. In order to hold a particular metal ion with high affinity and specificity, proteins form multidentate binding pockets designed to fulfill both the chemical and geometric bonding requirements of that metal. Metal recognition can be engineered into proteins for applications such as protein purification

Influence of Organic Structure Directing Agent Isomer Distribution on the Synthesis of SSZ-39

© 2015 American Chemical Society. The aluminosilicate molecular sieve with the AEI framework topology (SSZ-39) is currently of great interest for use in a number of important applications such as exhaust gas NOx reduction and the methanol-to-olefins reaction. It is likely that advances in the synthesis of this molecular sieve will be needed for applications to proceed. Here, dimethylpiperidine based organic structure directing agents (OSDAs) are used to prepare SSZ-39, and the influence of diastereo- and structural isomeric mixtures on the synthesis of SSZ-39 is reported. Although differences in the rates of molecular sieve formation as well as preferential isomer incorporation occur, the synthesis of SSZ-39 is possible over a wide range of isomeric mixtures. These findings demonstrate that the synthesis of SSZ-39 can be accomplished with OSDA isomer mixtures that naturally occur from the synthesis of the organic precursors used to prepare the OSDAs.status: publishe

Cu(II)-Binding properties of a cytochrome c with a synthetic metal-binding site: His-X_3-His in an α-helix

A metal‐binding site consisting of two histidines positioned His‐X_3‐His in an α‐helix has been engineered into the surface of Saccharomyces cerevisiae iso‐1‐cytochrome c. The synthetic metal‐binding cytochrome c retains its biological activity in vivo. Its ability to bind chelated Cu(II) has been characterized by partitioning in aqueous two‐phase polymer systems containing a polymer‐metal complex, Cu(II)IDA‐PEG, and by metal‐affinity chromatography. The stability constant for the complex formed between Cu(II)IDA‐PEG and the cytochrome c His‐X3‐His site is 5.3 × 104^ M^(−1), which corresponds to a chelate effect that contributes 1.5 kcal mol^(−1) to the binding energy. Incorporation of the His‐X_3‐His site yields a synthetic metal‐binding protein whose metal affinity is sensitive to environmental conditions that alter helix structure or flexibility

Cu(II)-Binding properties of a cytochrome c with a synthetic metal-binding site: His-X_3-His in an α-helix

A metal‐binding site consisting of two histidines positioned His‐X_3‐His in an α‐helix has been engineered into the surface of Saccharomyces cerevisiae iso‐1‐cytochrome c. The synthetic metal‐binding cytochrome c retains its biological activity in vivo. Its ability to bind chelated Cu(II) has been characterized by partitioning in aqueous two‐phase polymer systems containing a polymer‐metal complex, Cu(II)IDA‐PEG, and by metal‐affinity chromatography. The stability constant for the complex formed between Cu(II)IDA‐PEG and the cytochrome c His‐X3‐His site is 5.3 × 104^ M^(−1), which corresponds to a chelate effect that contributes 1.5 kcal mol^(−1) to the binding energy. Incorporation of the His‐X_3‐His site yields a synthetic metal‐binding protein whose metal affinity is sensitive to environmental conditions that alter helix structure or flexibility