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Solid-state NMR (ssNMR) spectroscopy facilitates the non-destructive characterization of structurally heterogeneous biomolecules in their native setting, for example, comprising proteins, lipids and polysaccharides. Here we demonstrate the utility of high and ultra-high field 1 H-detected fast MAS ssNMR spectroscopy, which exhibits increased sensitivity and spectral resolution, to further elucidate the atomic-level composition and structural arrangement of the cell wall of Schizophyllum commune, a mushroom-forming fungus from the Basidiomycota phylum. These advancements allowed us to reveal that Cu(II) ions and the antifungal peptide Cathelicidin-2 mainly bind to cell wall proteins at low concentrations while glucans are targeted at high metal ion concentrations. In addition, our data suggest the presence of polysaccharides containing N-acetyl galactosamine (GalNAc) and proteins, including the hydrophobin proteins SC3, shedding more light on the molecular make-up of cells wall as well as the positioning of the polypeptide layer. Obtaining such information may be of critical relevance for future research into fungi in material science and biomedical contexts.

Elucidating the reaction mechanism of a catalytic process is very challenging. Now, advanced solid-state nuclear magnetic resonance experiments demonstrate the importance of oxygenates to regulate the conversion of synthesis gas over an oxide–zeolite-based bifunctional catalyst material.

Membrane proteins are known to exert many essential biological functions by forming complexes in cell membranes. An example refers to the β-barrel assembly machinery (BAM), a 200 kDa pentameric complex containing BAM proteins A–E that catalyzes the essential process of protein insertion into the outer membrane of gram-negative bacteria. While progress has been made in capturing three-dimensional structural snapshots of the BAM complex, the role of the lipoprotein BamC in the complex assembly in functional lipid bilayers has remained unclear. We have devised a component-selective preparation scheme to directly study BamC as part of the entire BAM complex in lipid bilayers. Combination with proton-detected solid-state NMR methods allowed us to probe the structure, dynamics, and supramolecular topology of full-length BamC embedded in the entire complex in lipid bilayers. Our approach may help decipher how individual proteins contribute to the dynamic formation and functioning of membrane protein complexes in membranes.

Matrix effects in a fluid catalytic cracking (FCC) catalyst have been studied in terms of structure, accessibility, and acidity. An extensive characterization study into the structural and acidic properties of a FCC catalyst, its individual components (i.e., zeolite H‐Y, binder (boehmite/silica) and kaolin clay), and two model FCC catalyst samples containing only two components (i.e., zeolite‐binder and binder‐clay) was performed at relevant conditions. This allowed the drawing of conclusions about the role of each individual component, describing their mutual physicochemical interactions, establishing structure‐acidity relationships, and determining matrix effects in FCC catalyst materials. This has been made possible by using a wide variety of characterization techniques, including temperature‐programmed desorption of ammonia, infrared spectroscopy in combination with CO as probe molecule, transmission electron microscopy, X‐ray diffraction, Ar physisorption, and advanced nuclear magnetic resonance. By doing so it was, for example, revealed that a freshly prepared spray‐dried FCC catalyst appears as a physical mixture of its individual components, but under typical riser reactor conditions, the interaction between zeolite H‐Y and binder material is significant and mobile aluminum migrates and inserts from the binder into the defects of the zeolite framework, thereby creating additional Brønsted acid sites and restoring the framework structure., On the interplay between matrix and catalyst: A combination of advanced characterization techniques reveals that while a freshly prepared spray‐dried fluid catalytic cracking catalyst appears as a physical mixture of its individual components, significant matrix effects actually come into play under industrial riser reactor conditions, leading to changing Brønsted and Lewis acidity, pore accessibility as well as various structural changes.

Methane dehydroaromatization (MDA) is among the most challenging processes in catalysis science owing to the inherent harsh reaction conditions and fast catalyst deactivation. To improve this process, understanding the mechanism of the initial C−C bond formation is essential. However, consensus about the actual reaction mechanism is still to be achieved. In this work, using advanced magic-angle spinning (MAS) solid-state NMR spectroscopy, we study in detail the early stages of the reaction over a well-dispersed Mo/H-ZSM-5 catalyst. Simultaneous detection of acetylene (i.e., presumably the direct C−C bond-forming product from methane), methylidene, allenes, acetal, and surface-formate species, along with the typical olefinic/aromatic species, allow us to conclude the existence of at least two independent C−H activation pathways. Moreover, this study emphasizes the significance of mobility-dependent host–guest chemistry between an inorganic zeolite and its trapped organic species during heterogeneous catalysis.

The modes of deactivation -and the extent to which their properties can be restored- of two catalyst bodies used in cascade for bio-oil synthesis have been studied. These catalysts include a solid acid granulate (namely ZrO2/desilicated zeolite ZSM-5/attapulgite clay) employed in ex-situ catalytic fast pyrolysis of biomass, and a base extrudate (K-exchanged zeolite USY/attapulgite clay) for the subsequent bio-oil upgrading. Post-mortem analyses of both catalyst bodies with Raman spectroscopy and confocal fluorescence microscopy revealed the presence of highly poly-aromatic coke distributed in an egg-shell manner. Deactivation due to coke adsorption onto acid sites affected the zeolite ZSM-5-based catalyst, while for the base catalyst it is structural integrity loss, resulting from KOH-mediated zeolite framework collapse, the main deactivating factor. A hydrothermal regeneration process reversed the detrimental effects of coke in the acid catalyst, largely recovering catalyst acidity (∼80%) and textural properties (∼90%), but worsened the structural damage suffered by the base catalyst.

Among all catalytic natural gas valorization processes, methane dehydroaromatization (MDA) still has a great potential to be utilized at an industrial level. Although the use of Mo/H-ZSM-5 as an MDA catalyst was first reported almost three decades ago, the process is yet to be industrialized, because of its inherent challenges. In order to improve the overall catalytic performance and lifetime, the co-feeding of water constitutes a promising option, because of its abundance and nontoxicity. Although water’s (limited) positive influence on catalyst lifetime has earlier been exhibited, the exact course of action (like mechanism or the water effect on active sites) is yet to be established. To bridge this knowledge gap, in this work, we have performed an in-depth investigation to elucidate the effects of water co-feeding over a well-dispersed Mo/H-ZSM-5 catalyst by using an array of advanced characterization techniques (nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry-temperature-programmed oxidation/mass spectroscopy (TG-TPO/MS), scanning transmission electron microscopy (STEM), N2physisorption, Raman spectroscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES)). Our results demonstrate that the addition of water results in the occurrence of steam reforming (of both coke and methane) in parallel to MDA. Moreover, the presence of water affects the reducibility of Mo sites, as corroborated with computational analysis to examine the state and locality of Mo sites under various water levels and transformation of the catalyst structure during deactivation. We anticipate that our comprehensive study of the structure-function relationship on Mo/H-ZSM-5 under humid MDA conditions will be beneficial for the development of future methane valorization technologies.

Dynamic nuclear polarization (DNP) is a powerful method to enhance the sensitivity of solid-state magnetic nuclear resonance (ssNMR) spectroscopy. However, its biomolecular applications at high magnetic fields (preferably > 14 T) have so far been limited by the intrinsically low efficiency of polarizing agents and sample preparation aspects. Herein, we report a new class of trityl-nitroxide biradicals, dubbed SNAPols that combine high DNP efficiency with greatly enhanced hydrophilicity. SNAPol-1, the best compound in the series, shows DNP enhancement factors at 18.8 T of more than 100 in small molecules and globular proteins and also exhibits strong DNP enhancements in membrane proteins and cellular preparations. By integrating optimal sensitivity and high resolution, we expect widespread applications of this new polarizing agent in high-field DNP/ssNMR spectroscopy, especially for complex biomolecules.

In this paper we investigate a novel set of polarizing agents -- mixed-valence compounds -- by theoretical and experimental methods and demonstrate their performance in high-field Dynamic Nuclear Polarization (DNP) experiments in the solid state. Mixed-valence compounds constitute a group of molecules, in which molecular mobility persists even in solids. Consequently, such polarizing agents can be used to perform Overhauser-DNP experiments in solid-state, with favorable conditions for dynamic nuclear polarization formation at ultra-high magnetic fields., 4 pages, 6 figures

Catalyst deactivation due to coking is a major challenge in the catalytic fast pyrolysis (CFP) of biomass. Here, a multitechnique investigation of a technical Al2O3-bound ZSM-5-based extrudate catalyst, used for the CFP of pine wood and cellulose (at a reactor temperature of 500 °C), provided insight into the effects of extrusion, the catalytic pyrolysis process, and catalyst regeneration on the catalyst structure. As a result of a reduction in acidity and surface area due to the coking catalyst, the activity dropped drastically with increasing time-on-stream (TOS), as evidenced by a decrease in aromatics yield. Strikingly, confocal fluorescence microscopy at the single-particle level revealed that vapor components derived from whole biomass or just the cellulose component coke differently. While pine-wood-derived species mainly blocked the external area of the catalyst particle, larger carbon deposits were formed inside the catalyst's micropores with cellulose-derived species. Pyridine FT-IR and solid-state NMR spectroscopy demonstrated irreversible changes after regeneration, likely due to partial dealumination. Taken together with

We report the supramolecular assembly of artificial metalloenzymes (ArMs), based on the Lactococcal multidrug resistance regulator (LmrR) and an exogeneous copper(II)–phenanthroline complex, in the cytoplasm of E. coli cells. A combination of catalysis, cell‐fractionation, and inhibitor experiments, supplemented with in‐cell solid‐state NMR spectroscopy, confirmed the in‐cell assembly. The ArM‐containing whole cells were active in the catalysis of the enantioselective Friedel–Crafts alkylation of indoles and the Diels–Alder reaction of azachalcone with cyclopentadiene. Directed evolution resulted in two different improved mutants for both reactions, LmrR_A92E_M8D and LmrR_A92E_V15A, respectively. The whole‐cell ArM system required no engineering of the microbial host, the protein scaffold, or the cofactor to achieve ArM assembly and catalysis. We consider this a key step towards integrating abiological catalysis with biosynthesis to generate a hybrid metabolism., Artificial metalloenzymes were created by supramolecular assembly in the cytoplasm of E. coli cells. The cells were then applied to the enantioselective biocatalysis of a Friedel–Crafts alkylation of indoles (see picture) and a Diels–Alder reaction. Directed evolution of the artificial metalloenzymes inside the cells provided improved variants for both whole‐cell biocatalytic reactions.

The synthesis of many industrial bulk and fine chemicals frequently involves electrophilic aromatic substitution (SEAr) reactions. The most widely practiced example of the SEAr mechanism is the zeolite-catalysed ethylation of benzene, using ethylene as an alkylating agent. However, the current production route towards ethylbenzene is completely dependent on fossil resources, making the recent commercial successes in the zeolite-catalysed benzene ethylation process using bioethanol (instead of ethylene) very encouraging and noteworthy. Unfortunately, there is no information available on the reaction mechanism of this alternative synthesis route. Here, by employing a combination of advanced solid-state NMR spectroscopy and operando UV-Vis diffuse reflectance spectroscopy with on-line mass spectrometry, we have obtained detailed mechanistic insights into the bioethanol-mediated benzene ethylation process through the identification of active surface ethoxy species, surface-adsorbed zeolite–aromatic π-complexes, as well as the more controversial Wheland-type σ-complex. Moreover, we distinguish between rigid and mobile zeolite-trapped organic species, providing further evidence for distinctive host–guest chemistry during catalysis.

Dynamic nuclear polarization (DNP) enhanced solid‐state NMR (ssNMR) spectroscopy enables atomic‐level structural studies of isotope labeled proteins at physiologically relevant concentrations in mammalian cells, irrespective of the tumbling rate of the protein of interest, as reported by H. Ovaa, M. Baldus, and co‐workers in their Communication on page 12969 ff. In the absence of DNP, NMR sensitivity levels are insufficient to conduct such studies.

Elucidating at atomic level how proteins interact and are chemically modified in cells represents a leading frontier in structural biology. We have developed a tailored solid-state NMR spectroscopic approach that allows studying protein structure inside human cells at atomic level under high-sensitivity dynamic nuclear polarization (DNP) conditions. We demonstrate the method using ubiquitin (Ub), which is critically involved in cellular functioning. Our results pave the way for structural studies of larger proteins or protein complexes inside human cells, which have remained elusive to in-cell solution-state NMR spectroscopy due to molecular size limitations.

International audience; Zeolite-based catalysts are globally employed in many industrial processes, such as in crude-oil refining and in the production of bulk chemicals. However, to be implemented in industrial reactors efficiently, zeolite powders are required to be shaped in catalyst bodies. Scale-up of zeolite catalysts into such forms comes with side effects to its overall physicochem-ical properties and to those of its constituting components. Although fundamental research into "technical" solid catalysts is scarce, binder effects have been reported to significantly impact their catalytic properties and lifetime. Given the large number of additional (in)organic components added in the formulation, it is somehow surprising to see that there is a distinct lack of research into the unintentional impact organic additives can have on the properties of the zeolite and the catalyst bodies in general. Here, we systematically prepared a series of alumina-bound zeolite ZSM-5-based catalyst bodies, with organic additives such as peptizing, plasticizing, and lubricating agents, to rationalize their impacts on the physicochemical properties of the shaped catalyst bodies. By utilizing a carefully selected arsenal of bulk and high-spatial resolution multiscale characterization techniques, as well as specifically sized bioinspired fluorescent nanoprobes to study pore accessibility, we clearly show that, although the organic additives achieve their primary function of a mechanically robust material, uncontrolled processes are taking place in parallel. We reveal that the extrusion process can lead to zeolite dealumination (from acid peptizing treatment, and localized steaming upon calcination); meso-and macropore structural rearrangement (via burning-out of organic plasticizing and lubricating agents upon calcination); and abating of known alumina binder effects (via scavenging of Al species via chelating lubricating agents), which significantly impact catalytic performance. Understanding the mechanisms behind such effects in industrial-grade catalyst formulations can lead to enhanced design of these important materials, which can improve process efficiency in a vast range of industrial catalytic reactions.

Although industrialized, the mechanism for catalytic upgrading of bioethanol over solid-acid catalysts (that is, the ethanol-to-hydrocarbons (ETH) reaction) has not yet been fully resolved. Moreover, mechanistic understanding of the ETH reaction relies heavily on its well-known “sister-reaction” the methanol-to-hydrocarbons (MTH) process. However, the MTH process possesses a C 1 -entity reactant and cannot, therefore, shed any light on the homologation reaction sequence. The reaction and deactivation mechanism of the zeolite H-ZSM-5-catalyzed ETH process was elucidated using a combination of complementary solid-state NMR and operando UV/Vis diffuse reflectance spectroscopy, coupled with on-line mass spectrometry. This approach establishes the existence of a homologation reaction sequence through analysis of the pattern of the identified reactive and deactivated species. Furthermore, and in contrast to the MTH process, the deficiency of any olefinic-hydrocarbon pool species (that is, the olefin cycle) during the ETH process is also noted.

Understanding the 3-D distribution and nature of active sites in heterogeneous catalysts is critical to developing structure-function relationships. However, this is difficult to achieve in microporous materials as there is little relative z-contrast between active and inactive framework elements (e.g., Al, O, P, and Si), making them difficult to differentiate with electron microscopies. We have applied atom probe tomography (APT), currently the only nanometer-scale 3-D microscopy to offer routine light element contrast, to the methanol-to-hydrocarbons (MTH) catalyst SAPO-34, with Si as the active site, which may be present in the framework as either isolated Si species or clusters (islands) of Si atoms. 29Si solid-state NMR data on isotopically enriched and natural abundance materials are consistent with the presence of Si islands, and the APT results have been complemented with simulations to show the smallest detectable cluster size as a function of instrument spatial resolution and detector efficiency. We have identified significant Si-Si affinity in the materials, as well as clustering of coke deposited by the MTH reaction (13CH3OH used) and an affinity between Brønsted acid sites and coke. A comparison with simulations shows that the ultimate spatial resolution that can be attained by APT applied to molecular sieves is 0.5-1 nm. Finally, the observed 13C clusters are consistent with hydrocarbon pool mechanism intermediates that are preferentially located in regions of increased Brønsted acidity.

Zeolite activity and selectivity is often determined by the underlying proton and hydrogen-transfer reaction pathways. For the first time, we use single-molecule fluorescence microscopy to directly follow the real-time behavior of individual styrene-derived carbocationic species formed within zeolite ZSM-5. We find that intermittent fluorescence and remarkable photostability of carbocationic intermediates strongly depend on the local chemical environment imposed by zeolite framework and guest solvent molecules. The carbocationic stability can be additionally altered by changing para-substituent on the styrene moiety, as suggested by DFT calculations. Thermodynamically unstable carbocations are more likely to switch between fluorescent (carbocationic) and dark (neutral) states. However, the rate constants of this reversible change can significantly differ among individual carbocations, depending on their exact location in the zeolite framework. The lifetimes of fluorescent states and reversibility of the process can be additionally altered by changing the interaction between dimeric carbocations and solvated Brønsted acid sites in the MFI framework. Advanced multidimensional magic angle spinning solid-state NMR spectroscopy has been employed for the accurate structural elucidation of the reaction products during the zeolite-catalyzed dimerization of styrene in order to corroborate the single-molecule fluorescence microscopy data. This complementary approach of single-molecule fluorescence microscopy, NMR, and DFT collectively indicates that the relative stability of the carbocationic and the neutral states largely depends on the substituent and the local position of the Brønsted acid site within the zeolite framework. As a consequence, new insights into the host-guest chemistry between the zeolite and aromatics, in terms of their surface mobility and reactivity, have been obtained. ispartof: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY vol:140 issue:43 pages:14195-14205 ispartof: location:United States status: published

(1) H-detection can greatly improve spectral sensitivity in biological solid-state NMR (ssNMR), thus allowing the study of larger and more complex proteins. However, the general requirement to perdeuterate proteins critically curtails the potential of (1) H-detection by the loss of aliphatic side-chain protons, which are important probes for protein structure and function. Introduced herein is a labelling scheme for (1) H-detected ssNMR, and it gives high quality spectra for both side-chain and backbone protons, and allows quantitative assignments and aids in probing interresidual contacts. Excellent (1) H resolution in membrane proteins is obtained, the topology and dynamics of an ion channel were studied. This labelling scheme will open new avenues for the study of challenging proteins by ssNMR.

We report a novel proton-detected MAS solid-state NMR strategy based on 15N–15N proton assisted recoupling to detect the inter-nucleotide NH⋯N hydrogen bonds within the Watson–Crick base pairs of micro-crystallized dimeric RNA and to confirm the kissing-loop structure. This would contribute to advances in the structural determination of RNA using solid-state NMR.

© 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. The segregation of cellular surfaces in heterogeneous patches is considered to be a common motif in bacteria and eukaryotes that is underpinned by the observation of clustering and cooperative gating of signaling membrane proteins such as receptors or cha nnels. Such processes could represent an important cellular strategy to shape signaling activity. Hence, structural knowledge of the arrangement of channels or receptors in supramolecular assemblies represents a crucial step towards a better understanding of signaling across membranes. We herein report on the supramolecular organization of clusters of the K + channel KcsA in bacterial membranes, which was analyzed by a combination of DNP-enhanced solid-state NMR experiments and MD simulations. We used solid-state NMR spectroscopy to determine the channel–channel interface and to demonstrate the strong correlation between channel function and clustering, which suggests a yet unknown mechanism of communication between K + channels.

Disaccharides are well known for their membrane protective ability. Interaction between sugars and multi-component membranes, however, remains largely unexplored. Here, we combine molecular dynamics simulations and fluorescence microscopy to study the effect of mono- and disaccharides on membranes that phase separate into Lo and Ld domains. We find that non-reducing disaccharides, sucrose and trehalose, strongly destabilize the phase separation leading to uniformly mixed membranes as opposed to monosaccharides and reducing disaccharides. To unveil the driving force for this process, simulations were performed in which the sugar linkage was artificially modified. The availability of accessible interfacial binding sites that can accommodate the non-reducing disaccharides is key for their strong impact on lateral membrane organization. These exclusive interactions between the non-reducing sugars and the membranes may rationalize why organisms such as yeasts, tardigrades, nematodes, bacteria and plants accumulate sucrose and trehalose, offering cell protection under anhydrobiotic conditions. The proposed mechanism might prove to be a more generic way by which surface bound agents could affect membranes.

Recovery in K(+) channels, that is, the transition from the inactivated nonconductive selectivity filter conformation toward the conductive conformation, occurs on a time scale of the order of seconds, which is astonishingly long, given that the structural differences among the filter conformations are faint (1 Å). Computational studies and electrophysiological measurements suggested that buried water molecules bound behind the selectivity filter are at the origin of the slowness of recovery in K(+) channels. Using a combination of solid-state NMR spectroscopy (ssNMR) and long molecular dynamics simulations, we sketch a high-resolution map of the spatial and temporal distribution of water behind the selectivity filter of a membrane-embedded K(+) channel in two different gating modes. Our study demonstrates that buried water molecules with long residence times are spread all along the rear of the inactivated filter, which explains the recovery kinetics. In contrast, the same region of the structure appears to be dewetted when the selectivity filter is in the conductive state. Using proton-detected ssNMR on fully protonated channels, we demonstrate the presence of a pathway that allows for the interchange of buried and bulk water, as required for a functional influence of buried water on recovery and slow inactivation. Furthermore, we provide direct experimental evidence for the presence of additional ordered water molecules that surround the filter and that are modulated by the channel's gating mode.

Methanol‐to‐olefin (MTO) catalysis is a very active field of research because there is a wide variety of sometimes conflicting mechanistic proposals. An example is the ongoing discussion on the initial C−C bond formation from methanol during the induction period of the MTO process. By employing a combination of solid‐state NMR spectroscopy with UV/Vis diffuse reflectance spectroscopy and mass spectrometry on an active H‐SAPO‐34 catalyst, we provide spectroscopic evidence for the formation of surface acetate and methyl acetate, as well as dimethoxymethane during the MTO process. As a consequence, new insights in the formation of the first C−C bond are provided, suggesting a direct mechanism may be operative, at least in the early stages of the MTO reaction.

1H detection can significantly improve solid‐state NMR spectral sensitivity and thereby allows studying more complex proteins. However, the common prerequisite for 1H detection is the introduction of exchangeable protons in otherwise deuterated proteins, which has thus far significantly hampered studies of partly water‐inaccessible proteins, such as membrane proteins. Herein, we present an approach that enables high‐resolution 1H‐detected solid‐state NMR (ssNMR) studies of water‐inaccessible proteins, and that even works in highly complex environments such as cellular surfaces. In particular, the method was applied to study the K+ channel KcsA in liposomes and in situ in native bacterial cell membranes. We used our data for a dynamic analysis, and we show that the selectivity filter, which is responsible for ion conduction and highly conserved in K+ channels, undergoes pronounced molecular motion. We expect this approach to open new avenues for biomolecular ssNMR.

Incorporation of Ca in ZSM-5 results in a twofold increase of propylene selectivity (53%), a total light-olefin selectivity of 90%, and a nine times longer catalyst lifetime (throughput 792 g(MeOH)g(catalyst)(-1)) in the methanol-to-olefins (MTO) reaction. Analysis of the product distribution and theoretical calculations reveal that post-synthetic modification with Ca2+ leads to the formation of CaOCaOH+ that strongly weaken the acid strength of the zeolite. As a result, the rate of hydride transfer and oligomerization reactions on these sites is greatly reduced, resulting in the suppression of the aromatic cycle. Our results further highlight the importance of acid strength on product selectivity and zeolite lifetime in MTO chemistry.

Diatom biosilica is an inorganic/organic hybrid with interesting properties. The molecular architecture of the organic material at the atomic and nanometer scale has so far remained unknown, in particular for intact biosilica. A DNP-supported ssNMR approach assisted by microscopy, MS, and MD simulations was applied to study the structural organization of intact biosilica. For the first time, the secondary structure elements of tightly biosilica-associated native proteins in diatom biosilica were characterized in situ. Our data suggest that these proteins are rich in a limited set of amino acids and adopt a mixture of random-coil and β-strand conformations. Furthermore, biosilica-associated long-chain polyamines and carbohydrates were characterized, thereby leading to a model for the supramolecular organization of intact biosilica.

A combination of solid-state NMR techniques supported by EPR and SEM-EDX experiments was used to localize different carbon species (coke) in commercial fluid catalytic cracking catalysts. Aliphatic coke species formed during the catalytic process and aromatic coke species deposited directly from the feedstock respond differently to dynamic nuclear polarization signal enhancement in integral and crushed FCC particles, indicating that aromatic species are mostly concentrated on the outside of the catalyst particles, whereas aliphatic species are also located on the inside of the FCC particles. The comparison of solid-state NMR data with and without the DNP radical at low and ambient temperature suggests the proximity between aromatic carbon deposits and metals (mostly iron) on the catalyst surface. These findings potentially indicate that coke and iron deposit together, or that iron has a role in the formation of aromatic coke.

We show that selective labeling of proteins with protonated amino acids embedded in a perdeuterated matrix, dubbed 'proton clouds', provides general access to long-range contacts between nonexchangeable side chain protons in proton-detected solid-state NMR, which is important to study protein tertiary structure. Proton-cloud labeling significantly improves spectral resolution by simultaneously reducing proton line width and spectral crowding despite a high local proton density in clouds. The approach is amenable to almost all canonical amino acids. Our method is demonstrated on ubiquitin and the Î-barrel membrane protein BamA.

Wet-kneading is a technique commonly used for the synthesis of SiO2–MgO catalysts for the Lebedev ethanol-to-butadiene process, with catalyst performance known to depend heavily on the preparation parameters used in this method. Here, the large influence of Mg precursor and MgO content on morphology, chemical structure (as determined by TEM(-EDX), FT-IR, XRD and solid-state 1H–29Si cross-polarized MAS NMR), and on catalyst performance is demonstrated. The Mg precursor used is found to influence the extent of magnesium silicate formation during wet-kneading, as estimated from TEM and FT-IR, which, in turn, was found to correlate with catalyst performance. Accordingly, the catalyst synthesized from a nanosized Mg(OH)2 precursor (SiO2–MgO (III)nano), showing the highest degree of chemical contact between the SiO2 and MgO components, gave the highest butadiene yield. Variation of the Mg/Si ratio in a series of SiO2–MgO (III)nano materials showed a volcano-type dependence of the butadiene yield on MgO content. 1H–29Si CP-MAS NMR studies allowed for the identification of the type and an estimation of the amount of magnesium silicates formed during wet-kneading. Here, we argue that the structural characteristics of the hydrous magnesium silicates, lizardite and talc, formed during catalyst preparation, together with the ratio of the magnesium silicates to MgO, determine the overall acid/base properties of the SiO2–MgO (III)nano catalyst materials and as a result, catalyst performance.

Nanovesicles self-assembled from amphiphilic peptides are promising candidates for applications in drug delivery. However, complete high-resolution data on the local and supramolecular organization of such materials has been elusive thus far, which is a substantial obstacle to their rational design. In the absence of precise information, nanovesicles built of amphiphilic "lipid-like" peptides are generally assumed to resemble liposomes that are organized from bilayers of peptides with a tail-to-tail ordering. Using the nanocarrier formed by the amphiphilic self-assembling peptide 2 (SA2 peptide) as an example, we derive the local and global organization of a multimega-Dalton peptide-based nanocarrier at high molecular detail and at close-to physiological conditions. By integrating a multitude of experimental techniques (solid-state NMR, AFM, SLS, DLS, FT-IR, CD) with large- and multiscale MD simulations, we show that SA2 nanocarriers are built of interdigitated antiparallel β-sheets, which bear little resemblance to phospholipid liposomes. Our atomic level study allows analyzing the vesicle surface structure and dynamics as well as the intermolecular forces between peptides, providing a number of potential leads to improve and tune the biophysical properties of the nanocarrier. The herein presented approach may be of general utility to investigate peptide-based nanomaterials at high-resolution and at physiological conditions. (Figure Presented).