Alveolar antral artery: cone beam computed tomography study and clinical context.

Purpose: Anastomosis between posterior superior alveolar artery and infraorbital artery can go through bony canal in the lateral wall of the maxilla. This artery is called alveolar antral artery. It can complicate lateral sinus lift procedure by bleeding and hemosinus formation or bone graft wash out. The artery can also go in soft tissues where is not visible on cone beam computed tomography. In previous studies, the relation of this artery to sinus floor or alveolar process was measured. These structures are highly unstable during lifetime and after tooth loss. The aim of this study is to study presence and relations of bony canal in the lateral maxillary wall, to characterize the group of patients which is more likely to have bone canal in the lateral maxilla. The aim and the novelty of this study is the describing of the relationship of the bony canal to the more stable structure of hard palate and describing the relation of presence of bony canal on width of maxillary sinus, and to facilitate the prediction of presence of the alveolar antral artery. Materials: The cone beam computed tomography scans of the patients (251 in number) of the university hospital were examined for presence of alveolar antral artery (148 was fulfilled inclusion criteria), patient were characterized by gender, age, and sinus type (wide, average, narrow). The diameter of the bony canal and its relation to the level of sinus floor and hard palate were measured. Results: The cone beam computed tomography scans of 148 patients, out of it 55 man (37,2%) and 93 women (62,8%). Bony canal containing alveolar anastomosis was found in 69 cases (57,0%). Presence of the bony canal in the lateral wall of maxillae showed statistical probability depending on age with p = 0, 064 according to Mann-Whitney test. The older patients have more likely the bony canal. The presence of the alveolar antral artery was found more likely in the wide sinuses. The hard palate level can serve as a prediction point of alveolar antral artery only in first molar and second premolar region. In accordance with previous studies the width of bony canal is significantly higher in group of man (p = 0, 015). There was found a correlation between smaller distance of bony canal from sinus floor in the presence of teeth (p = 0, 067). After tooth loss the distance between sinus floor and bony canal increases, but the distance of bony canal to hard palate level stays constant. This can be explained hypothetically so that periodontal ligaments and root surface acts as a barrier for sinus pneumatization. Conclusion: Lateral sinus lifting in some cases can be unenviable, the knowledge about alveolar antral artery anatomy can reduce the risk of arterial bleeding. The cone-beam computed tomography is a routine examination prior to augmentation surgery and therefore the data obtained from it has an impact on clinical practice.

Site Selectivity for the Spin States and Spin Crossover in Undecanuclear Heterometallic Cyanido-Bridged Clusters.

Polynuclear molecular clusters offer an opportunity to design new hierarchical switchable materials with collective properties, based on variation of the chemical composition, size, shapes, and overall building blocks organization. In this study, we rationally designed and constructed an unprecedented series of cyanido-bridged nanoclusters realizing new undecanuclear topology: FeII[FeII(bzbpen)]6[WV(CN)8]2[WIV(CN)8]2·18MeOH (1), NaI[CoII(bzbpen)]6[WV(CN)8]3[WIV(CN)8]·28MeOH (2), NaI[NiII(bzbpen)]6[WV(CN)8]3[WIV(CN)8]·27MeOH (3), and CoII[CoII(R/S-pabh)2]6[WV(CN)8]2[WIV(CN)8]2·26MeOH [4R and 4S; bzbpen = N1,N2-dibenzyl-N1,N2-bis(pyridin-2-ylmethyl)ethane-1,2-diamine; R/S-pabh = (R/S)-N-(1-naphthyl)-1-(pyridin-2-yl)methanimine], of size up to 11 nm3, ca. 2.0 × 2.2 × 2.5 nm (1-3) and ca. 1.4 × 2.5 × 2.5 nm (4). 1, 2, and 4 exhibit site selectivity for the spin states and spin transition related to the structural speciation based on subtle exogenous and endogenous effects imposed on similar but distinguishable 3d metal-ion-coordination moieties. 1 exhibits a mid-temperature-range spin-crossover (SCO) behavior that is more advanced than the previously reported SCO clusters based on octacyanidometallates and an onset of SCO behavior close to room temperature. The latter feature is also present in 2 and 4, which suggests the emergence of CoII-centered SCO not observed in previous bimetallic cyanido-bridged CoII-WV/IV systems. In addition, reversible switching of the SCO behavior in 1 via a single-crystal-to-single-crystal transformation during desolvation was also documented.

The Double Capsule Phenomenon in a Case Series and its Relationship with the Macro-Textured Breast Implant.

BACKGROUND: Silicone breast augmentation remains one of the most common aesthetic surgery procedures, and 2022 marks the 60th anniversary of the first case. Recent studies suggest a link between double capsule (DC) formation and macro-textured devices. METHODS: Between 2010 and 2015, 268 aesthetic patients underwent bilateral mammary prosthesis exchange for indications including PIP exchange, adverse capsular contracture and ultrasonographic evidence of rupture. All surgery, in the form of implant exchange and capsulectomy, was undertaken by the senior author using standard techniques. A retrospective review was undertaken, and data analysed with descriptive statistics and Fisher's exact and Mann-Whitney U tests. RESULTS: Of 268 patients identified, 40 (14.9%) showed some degree of capsular duplication and bilateral involvement was marginally more common (52.5%). Two macroscopic patterns of duplication were observed: complete and subtotal. Complete DCs correlated with a clinical triad of extreme firmness, mobility and minimal-to-no pain. Whilst a wide range of manufacturers was represented, macro-textured devices were associated with the highest DC prevalence (58.3% vs. 5.6%) (Fisher's exact test p < 0.00001). Patients with DC had been implanted for less than half the time, median 52 versus. 120 months (p = 0.0003) of those without. DISCUSSION: An elevated prevalence of duplicate capsules in macro-textured prostheses is reconfirmed in addition to a novel symptom constellation that may assist with clinical diagnosis. Our study reinforces the aetiopathogenic influence of the elastomer in DC formation and reports DC for the first time in non-macrotextured implants. Single-surgeon cohort of 268 consecutive patients with 532 implants Statistically significant association of macro-textured devices with DC Statistically significant reduced duration of implantation of macro-textured devices First report of DC in non-macro-textured devices LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Development of a Web-Based System to Report Medication-Related Adverse Effects: Design and Usability Study.

BACKGROUND: Medicine use is the most common intervention in health care. The frequency with which medicines are used means medication-related problems are very common. One common type of medication-related problems is adverse drug events, which are unintended and harmful effects associated with use of medicines. Reporting of adverse drug events to regulatory authorities is important for evaluation of safety of medicines; however, these adverse effects are frequently unreported due to various factors, including lack of consumer-friendly reporting tools. OBJECTIVE: The aim of this study was to develop a user-friendly digital tool for consumers to report medication-related adverse effects. METHODS: The project consisted of 3 parts: (1) content development, including a systematic literature search; (2) iterative system development; and (3) usability testing. The project was guided by participatory design principles, which suggest involving key stakeholders throughout the design process. The first 2 versions were developed as a mobile app and were tested with end users in 2 workshops. The third version was developed as a web application and was tested with consumers who were taking regular medicines. Consumers were asked to complete a modified version of the mHealth app usability questionnaire (MAUQ), an 18-item questionnaire with each item scored using a 7-point Likert scale ranging from 0 (strongly disagree) to 7 (strongly agree). The MAUQ assessed 3 subscales including ease of use (5 items), interface and satisfaction (7 items), and usefulness (6 items). Continuous variables were reported as mean (SD) values, whereas categorical variables were presented as frequencies (percentages). Data analysis was conducted in Microsoft Excel. RESULTS: The content for the system was based on a systematic literature search and short-listing of questions, followed by feedback from project team members and consumers. Feedback from consumers in the 2 workshops were incorporated to improve the functionality, visual design, and stability of the third (current) version. The third version of the system was tested with 26 consumers. A total of 79% (N=307/390) of all responses on the MAUQ were scored 6 or 7, indicating that users generally strongly agree with the usability of the system. When looking at the individual domains, the system had an average score of 6.3 (SD 0.9) for "ease of use," 6.3 (SD 0.8) for "interface and satisfaction," and 5.2 (SD 1.4) for "usefulness." CONCLUSIONS: The web-based system for medicine adverse effects reporting is a user-friendly tool developed using an iterative participatory design approach. Future research includes further improving the system, particularly the usefulness of the system, as well as testing the scalability and performance of the system in practice.

1H-Detected Biomolecular NMR under Fast Magic-Angle Spinning.

Since the first pioneering studies on small deuterated peptides dating more than 20 years ago, 1H detection has evolved into the most efficient approach for investigation of biomolecular structure, dynamics, and interactions by solid-state NMR. The development of faster and faster magic-angle spinning (MAS) rates (up to 150 kHz today) at ultrahigh magnetic fields has triggered a real revolution in the field. This new spinning regime reduces the 1H-1H dipolar couplings, so that a direct detection of 1H signals, for long impossible without proton dilution, has become possible at high resolution. The switch from the traditional MAS NMR approaches with 13C and 15N detection to 1H boosts the signal by more than an order of magnitude, accelerating the site-specific analysis and opening the way to more complex immobilized biological systems of higher molecular weight and available in limited amounts. This paper reviews the concepts underlying this recent leap forward in sensitivity and resolution, presents a detailed description of the experimental aspects of acquisition of multidimensional correlation spectra with fast MAS, and summarizes the most successful strategies for the assignment of the resonances and for the elucidation of protein structure and conformational dynamics. It finally outlines the many examples where 1H-detected MAS NMR has contributed to the detailed characterization of a variety of crystalline and noncrystalline biomolecular targets involved in biological processes ranging from catalysis through drug binding, viral infectivity, amyloid fibril formation, to transport across lipid membranes.

NMR Assignment of Methyl Groups in Immobilized Proteins Using Multiple-Bond 13C Homonuclear Transfers, Proton Detection, and Very Fast MAS.

In nuclear magnetic resonance spectroscopy of proteins, methyl protons play a particular role as extremely sensitive reporters on dynamics, allosteric effects, and protein-protein interactions, accessible even in high-molecular-weight systems approaching 1 MDa. The notorious issue of their chemical shift assignment is addressed here by a joint use of solid-state 1H-detected methods at very fast (nearly 100 kHz) magic-angle spinning, partial deuteration, and high-magnetic fields. The suitability of a series of RF schemes is evaluated for the efficient coherence transfer across entire 13C side chains of methyl-containing residues, which is key for establishing connection between methyl and backbone 1H resonances. The performance of ten methods for recoupling of either isotropic 13C-13C scalar or anisotropic dipolar interactions (five variants of TOBSY, FLOPSY, DIPSI, WALTZ, RFDR, and DREAM) is evaluated experimentally at two state-of-the-art magic-angle spinning (55 and 94.5 kHz) and static magnetic field conditions (18.8 and 23.5 T). Model isotopically labeled compounds (alanine and Met-Leu-Phe tripeptide) and ILV-methyl and amide-selectively protonated, and otherwise deuterated chicken α-spectrin SH3 protein are used as convenient reference systems. Spin dynamics simulations in SIMPSON are performed to determine optimal parameters of these RF schemes, up to recently experimentally attained spinning frequencies (200 kHz) and B 0 field strengths (28.2 T). The concept of linearization of 13C side chain by appropriate isotope labeling is revisited and showed to significantly increase sensitivity of methyl-to-backbone correlations. A resolution enhancement provided by 4D spectroscopy with non-uniform (sparse) sampling is demonstrated to remove ambiguities in simultaneous resonance assignment of methyl proton and carbon chemical shifts.

Czech and Slovak Dental Students' Oral Health-Related Knowledge, Attitudes, and Behaviours (KAB): Multi-Country Cross-Sectional Study.

Dentists play a key role in the primary prevention of oral diseases and related systemic complications; therefore, their views on behavioural interventions need to be aligned with the current agendas for oral health. Likewise, dental students' oral health-related knowledge, attitudes, and behaviours (KAB) are of practical importance, as they are the future opinion leaders for oral health in their respective communities. A cross-sectional survey-based study was designed to evaluate the oral health KAB of dental students in both the Czech Republic and Slovakia. The study utilized translated versions of the Hiroshima University Dental Behavioural Inventory (HU-DBI), and it aimed to recruit students from all Czech and Slovak dental schools. A total of 487 students were included in this study, out of which 372 (76.4%) were females, 271 (55.6%) were enrolled in preclinical years, 68 (14%) reported smoking tobacco at least once a week, and 430 (88.3%) reported problematic internet use. The mean HU-DBI score of Czech and Slovak dental students (8.18 ± 1.80) was comparable with the previously reported scores of dental students in Nordic and Western European countries. Czech students (9.34 ± 1.29) had a significantly higher score than their Slovak counterparts (7.56 ± 1.73). In both countries, preclinical students (8.04 vs. 8.35), the students who reported tobacco smoking (7.63 vs. 8.27), and those who reported problematic internet use (8.11 vs. 8.70) had significantly lower HU-DBI scores than their counterparts, respectively. In the Czech Republic, the significant increases in HU-DBI scores occurred after the first academic year when the students received preventive dentistry courses; therefore, one can put forward that early implementation of preventive elements in undergraduate dental curricula may yield better and more sustainable oral health gains for the students. Future research on Czech and Slovak dental curricula need to re-evaluate the oral hygiene and anti-smoking components and their impact on students' views and attitudes.

Survival of Prosthodontic Restorations Luted with Resin-Based versus Composite-Based Cements: Retrospective Cohort Study.

The purpose of this study was to evaluate clinical performance, survival, and complications of indirect composite inlays, onlays, and overlays on posterior teeth. Digital records of 282 patients treated between 2014 and 2018 were accessed and analyzed retrospectively. The included patients received 469 composite restorations luted with seven different resin-based types of cement, i.e., Filtek Ultimate Flow, Enamel Plus, Relyx Ultimate, Harvard Premium Flow, Relyx Unicem, Filtek Bulk Fill Flowable, and Filtek Ultimate. The restorations had been clinically and radiographically evaluated annually. The mechanical and clinical complications, e.g., debonding, fracture, and secondary caries, were evaluated and recorded. The examined restorations exhibited a high survival rate (84.9%), and failure was found in only 71 cases. Fracture was the most common cause (n = 36), followed by prosthetic work release (n = 19) and secondary caries (n = 16). There was a statistically significant difference between failure and cement material (Sig. < 0.001); the composite-based cements (87.2%) had a high survival rate compared to the resin-based cement (72.7%). Similarly, the cements with high viscosity (90.2%) had significantly higher survival rates than the low-viscosity cements (78.9%). Moreover, onlays showed higher longevity compared to overlays (Sig. = 0.007), and patients aged under 55 years showed less complications (Sig. = 0.036). Indirect composite restoration was a successful solution to tooth structure loss. The material of the cementation is an important part of the success. Higher survival rate was found in our study when the fixation materials with high viscosity were used, thus suggesting using these materials with indirect restorations. Composite-based cements had significantly higher survival rate than resin-based cements.

Intramolecular rotations and electronic states of iron in the iron bis(dicarbollide) complex Fe[(C2B9H11)2] studied by a 57Fe nuclear probe and computational methods.

Mössbauer spectroscopy of iron(III) bis(dicarbollide) (1) and its adduct (2) revealed low spin FeIII in 1 and surprisingly FeII in 2. In 1, the (C2B9H11) groups rotate at room temperature with a frequency of 107 Hz, getting across the energy barrier of 24 meV. Numerical simulations showed a gradient of electric charge in 2, which may explain the FeII-like character in 2.

Effectiveness of dentin pre-treatment on bond strength of two self-adhesive resin cements compared to an etch-and-rinse system: an in vitro study.

STATEMENT OF PROBLEM: It has been shown that selective etching improves the bond strength of some self-adhesive resin cements to enamel. The same has yet to be determined with dentin pre-treatment. PURPOSE: To evaluate the tensile bond strength of two self-adhesive resin cements after two dentin surface pre-treatments, and also to analyze the cement/dentin interface. MATERIAL AND METHODS: One hundred and twelve human third molars were extracted. The teeth were distributed into seven groups (n = 16). Maxcem Elite Chroma (MAX) (Kerr, Scafati, Italy) and Relyx U200 (RLX) (3M ESPE, Neuss, Germany) were used without pre-treatment or with two dentin pre-treatments (polyacrylic acid or phosphoric acid). A conventional etch-and-rinse (EAR) luting cement, NX3 Nexus (NX3) (Kerr, Scafati, Italy), was used as an external control group. Before testing, all specimens were stored in distilled water for 24 hours. Three specimens from each group were prepared for scanning electron microscopy observation (SEM). A tensile bond strength test (TBS) was performed for the remaining samples. The data were statistically analyzed using the Kruskal-Wallis test and Pairwise comparisons using the Wilcoxon rank sum test. RESULTS: MAX without pre-treatment and with phosphoric acid etching attained statistically similar bond strengths to NX3 (P > 0.05). There was a statistical difference (P = 0.00488) between RLX without pre-treatment (5.62 MPa) and NX3 (10.88 MPa). Phosphoric acid pre-treatment increases the bond strength values of RLX to a strength that is comparable to NX3 (P > 0.05). The lowest tensile bond strength (TBS) was attained after the application of polyacrylic acid with MAX (1.98 MPa). No statistical differences were found between the RLX bond strength values after polyacrylic acid treatment and RLX without pre-treatment or NX3 (P > 0.05). SEM observations disclosed an enhanced potential of the self-adhesive cements to infiltrate into dentin tubules and form resin tags when applied after phosphoric acid pre-treatment. The failure mode was dominantly adhesive. CONCLUSIONS: On dentin, the self-adhesive resin cement MAX might be an effective alternative to conventional resin cement. Etching the dentin with phosphoric acid does not have a negative effect on the bond strength of MAX to dentin. On the other hand, phosphoric acid improved the bond strength of RLX when compared to EAR cement.

Backbone assignment of crystalline E. coli maltose binding protein.

The E.coli maltose binding protein (MBP) is a 42.5 kDa molecule widely employed in many biotechnology applications. Because of its molecular size, it has become the main model system for the development of solution NMR methods adapted to large biomolecular targets. Here, we report virtually complete (~ 90%) backbone resonance assignments obtained on a microcrystalline sample of MBP with 1H-detected solid-state NMR at fast (> 100 kHz) magic-angle spinning. We additionally present the detailed description of the methodology employed for the preparation of the sample and the acquisition and analysis of the NMR spectra. The chemical shifts, obtained with a single uniformly 15N, 13C-labelled and fully-protonated sample and about 2 weeks on a 800 MHz NMR spectrometer, have been deposited to the BMRB under the accession number 50089.

Structural and molecular basis of cross-seeding barriers in amyloids.

Neurodegenerative disorders are frequently associated with ß-sheet-rich amyloid deposits. Amyloid-forming proteins can aggregate under different structural conformations known as strains, which can exhibit a prion-like behavior and distinct pathophenotypes. Precise molecular determinants defining strain specificity and cross-strain interactions (cross-seeding) are currently unknown. The HET-s prion protein from the fungus Podospora anserina represents a model system to study the fundamental properties of prion amyloids. Here, we report the amyloid prion structure of HELLF, a distant homolog of the model prion HET-s. We find that these two amyloids, sharing only 17% sequence identity, have nearly identical ß-solenoid folds but lack cross-seeding ability in vivo, indicating that prion specificity can differ in extremely similar amyloid folds. We engineer the HELLF sequence to explore the limits of the sequence-to-fold conservation and to pinpoint determinants of cross-seeding and prion specificity. We find that amyloid fold conservation occurs even at an exceedingly low level of identity to HET-s (5%). Next, we derive a HELLF-based sequence, termed HEC, able to breach the cross-seeding barrier in vivo between HELLF and HET-s, unveiling determinants controlling cross-seeding at residue level. These findings show that virtually identical amyloid backbone structures might not be sufficient for cross-seeding and that critical side-chain positions could determine the seeding specificity of an amyloid fold. Our work redefines the conceptual boundaries of prion strain and sheds light on key molecular features concerning an important class of pathogenic agents.

Room-Temperature Bistability in a Ni-Fe Chain: Electron Transfer Controlled by Temperature, Pressure, Light, and Humidity.

Bistable and stimuli-responsive molecule-based materials are promising candidates for the development of molecular switches and sensors for future technologies. The CN-bridged {NH4 [Ni(cyclam)][Fe(CN)6 ]⋅5 H2 O}n chain exists in two valence states: NiII -FeIII (1HT ) and NiIII -FeII (1LT ) and shows unique multiresponsivity under ambient conditions to various stimuli, including temperature, pressure, light, and humidity, which generate measurable response in the form of significant changes in magnetic susceptibility and color. The electron-transfer phase transition 1LT ↔1HT shows room-temperature thermal hysteresis, can be induced by irradiation, and shows high sensitivity to small applied pressure, which shifts it to higher temperatures. Additionally, it can be reversibly turned off by dehydration to the {NH4 [NiII (cyclam)][FeIII (CN)6 ]}n (1 d) phase, which features the NiII -FeIII valence state over the whole temperature range, but responds to pressure by yielding NiIII -FeII above 1.06 GPa.

Tuning of the phase transition between site selective SCO and intermetallic ET in trimetallic magnetic cyanido-bridged clusters.

A series of crystalline phases composed of trimetallic 3d-5d-5d' {Fe9[Re(CN)8]6-x[W(CN)8]x(MeOH)24}·yMeOH (x = 1 (1), 2 (2), 3 (3), 4 (4) and 5 (5); y = 10-15) clusters were obtained by altering the octacyanidometalate composition. The temperature dependent studies involving SC XRD, SQUID magnetic measurements, IR spectroscopy and 57Fe Mössbauer spectroscopy revealed reversible phase transition with the retention of single crystal character in each congener. The transition was assisted by reversible spin-crossover (SCO) HSFeII↔LSFeII transition at the central Fe1(ii) site for Fe9Re5W1 (1), Fe9Re4W2 (2), Fe9Re3W3 (3) and Fe9Re2W4 (4). In contrast, the tungsten-rich congener Fe9Re1W5 (5) exhibited nontrivial behavior with the SCO transition being stopped halfway through the cooling process, to be completed with single electron transfer (ET) from the external Fe2(ii) center towards one of the neighboring W(v) sites. The critical temperature Tc of SCO has been systematically increased from 193 K (1) to 247 K (4). All experimental data indicate the domination of the Fe(ii)-W(v) valence states in all crystals 1-5, however, with increasing quantity of [W(CN)8]3- (and decreasing quantity of [Re(CN)8]3-), the valence equilibrium Fe(ii)-W(v) ↔ Fe(iii)-W(iv) was systematically shifted to the right, starting from congener 3. The overall electronic configuration at low temperatures and variable amounts and location of spin carriers along the whole series suggest the remarkable competition between magnetic super-exchange Fe(ii)-CN-W(v) interactions and intermolecular interactions. The observed behavior is in line with the information collected previously for the bimetallic congeners Fe9Re6 and Fe9W6, to shed light on the role of the mixed tri-metallic composition in changing the properties observed for the relevant bimetallic cyanido-bridged skeletons.

A ß-barrel for oil transport through lipid membranes: Dynamic NMR structures of AlkL.

The protein AlkL is known to increase permeability of the outer membrane of bacteria for hydrophobic molecules, yet the mechanism of transport has not been determined. Differing crystal and NMR structures of homologous proteins resulted in a controversy regarding the degree of structure and the role of long extracellular loops. Here we solve this controversy by determining the de novo NMR structure in near-native lipid bilayers, and by accessing structural dynamics relevant to hydrophobic substrate permeation through molecular-dynamics simulations and by characteristic NMR relaxation parameters. Dynamic lateral exit sites large enough to accommodate substrates such as carvone or octane occur through restructuring of a barrel extension formed by the extracellular loops.

Resonance assignment of the outer membrane protein AlkL in lipid bilayers by proton-detected solid-state NMR.

Most commonly small outer membrane proteins, possessing between 8 and 12 ß-strands, are not involved in transport but fulfill diverse functions such as cell adhesion or binding of ligands. An intriguing exception are the 8-stranded ß-barrel proteins of the OmpW family, which are implicated in the transport of small molecules. A representative example is AlkL from Pseudomonas putida GPoI, which functions as a passive importer of hydrophobic molecules. This role is of high interest with respect to both fundamental biological understanding and industrial applications in biocatalysis, since this protein is frequently utilized in biotransformation of alkanes. While the transport function of AlkL is generally accepted, a controversy in the transport mechanism still exists. In order to address this, we are pursuing a structural study of recombinantly produced AlkL reconstituted in lipid bilayers using solid-state NMR spectroscopy. In this manuscript we present 1H, 13C and 15N chemical shift assignments obtained via a suite of 3D experiments employing high magnetic fields (1 GHz and 800 MHz) and the latest magic-angle spinning (MAS) approaches at fast (60-111) kHz rates. We additionally analyze the secondary structure prediction in comparison with those of published structures of homologous proteins.

Automated Backbone NMR Resonance Assignment of Large Proteins Using Redundant Linking from a Single Simultaneous Acquisition.

Thanks to magic-angle spinning (MAS) probes with frequencies of 60-100 kHz, the benefit of high-sensitivity 1H detection can now be broadly realized in biomolecular solid-state NMR for the analysis of microcrystalline, sedimented, or lipid-embedded preparations. Nonetheless, performing the assignment of all resonances remains a rate-limiting step in protein structural studies, and even the latest optimized protocols fail to perform this step when the protein size exceeds ∼20 kDa. Here, we leverage the benefits of fast (100 kHz) MAS and high (800 MHz) magnetic fields to design an approach that lifts this limitation. Through the creation, conservation, and acquisition of independent magnetization pathways within a single triple-resonance MAS NMR experiment, a single self-consistent data set can be acquired, providing enhanced sensitivity, reduced vulnerability to machine or sample instabilities, and highly redundant linking that supports fully automated peak picking and resonance assignment. The method, dubbed RAVASSA (redundant assignment via a single simultaneous acquisition), is demonstrated with the assignment of the largest protein to date in the solid state, the 42.5 kDa maltose binding protein, using a single fully protonated microcrystalline sample and 1 week of spectrometer time.

Protein NMR Resonance Assignment without Spectral Analysis: 5D SOlid-State Automated Projection SpectroscopY (SO-APSY).

Narrow proton signals, high sensitivity, and efficient coherence transfers provided by fast magic-angle spinning at high magnetic fields make automated projection spectroscopy feasible for the solid-state NMR analysis of proteins. We present the first ultrahigh dimensional implementation of this approach, where 5D peak lists are reconstructed from a number of 2D projections for protein samples of different molecular sizes and aggregation states, which show limited dispersion of chemical shifts or inhomogeneous broadenings. The resulting datasets are particularly suitable to automated analysis and yield rapid and unbiased assignments of backbone resonances.

Site-Selective Photoswitching of Two Distinct Magnetic Chromophores in a Propeller-Like Molecule To Achieve Four Different Magnetic States.

Magnetic photoswitching is a highly important but relatively rare phenomenon for enabling optical writing/reading of the magnetic state of a molecule. In this work, an unprecedented site-selective double photoswitching is reported from the assembly of two different "photomagnetic chromophores" into a single hexanuclear molecule: namely, a spin-crossover Fe(II) center exhibiting light-induced excited spin state trapping (LIESST) and a photochemically active octacyanometalate(IV) unit. Four different magnetization levels are accessible through the appropriate combination of violet/red light and temperature, results that highlight the potential of photomagnetic molecules as future molecular memory cells.