Controlled protein hydrolysis is an important procedure in proteomics applications and is used to aid the understanding of protein structure and function. The hydrolysis of hydrophobic proteins is particularly challenging, as due to their poor solubility the use of surfactants, which typically inactivate natural enzymes, is often required. Such limitations of natural enzymes prompted the development of chemical catalysts for the selective hydrolysis of proteins. In this study, the nanozymatic potential of MOF-808, a Zr 6 O 8 based metal organic framework, has been investigated towards protein hydrolysis in the presence of several surfactants which differ in structure and polarity. The influence of ionic SDS (sodium dodecyl sulfate), neutral TX-100 (Triton X-100) and zwitterionic Zw3-12 (ndodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate) and CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) surfactants on the hydrolysis of horse heart myoglo-bin in the presence of MOF-808 has been examined. The hydrolysis of horse heart myoglobin by MOF-808 was followed using sodium dodecyl sulfate poly(acrylamide) gel electrophoresis (SDS-PAGE), which showed that nanozymatic activity of MOF-808 can be tuned by using appropriate surfactants. To understand the observed reactivity patterns, the interactions between surfactant, MOF and protein were further investigated using a range of spectroscopic methods, which included Dynamic Light Scattering (DLS), 1 H NMR, UV-Vis, Circular Dichroism and UV-Vis Spectroscopy. While the presence of SDS increased the number of observed peptide fragments due to protein unfolding and increased protein-MOF interaction, the use of zwitterionic and neutral surfactant reduced the hydrolytic efficiency, most likely by hindering the efficient protein-MOF interaction.
Transition-metal-catalyzed amide-bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol.%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further high-resolution mass spectrometry (HRMS) analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.
The Front Cover shows the interaction of myoglobin protein, represented by a bee, with Zr‐MOF‐808, represented by the honeycomb structure. In nature the relation between a bee and a honeycomb is a favorable interaction, and the same can be said for the interaction between myoglobin and MOF‐808. The protein is readily adsorbed on the MOF, which results in hydrolysis of the protein, but also some loss of substrate occurs due to adsorption onto the MOF. When surfactants (a second insect) are introduced, the protein‐MOF interactions are affected, resulting in changes to protein hydrolysis patterns and adsorption. This study investigates the protein‐MOF‐surfactant triangle to determine how the character of the surfactant alters this relationship and affects the subsequent hydrolysis. We wish to thank David Salazar Marcano for the design. More information can be found in the Research Article by T. N. Parac‐Vogt and co‐workers.
Transition-metal-catalyzed amide bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further HR-MS analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.
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