Pub Date : 2025-02-04DOI: 10.1016/j.ssnmr.2025.101993
Neethu Thomas , Claire Welton , Tomasz Pawlak , Parth Raval , Julien Trébosc , Sheetal K. Jain , G.N. Manjunatha Reddy
A cross-polarization 2H–1H isotope correlation spectroscopy (CP-iCOSY) approach is presented for characterizing a deuterated amino acid, pharmaceutical compound and a solid formulation. This can be achieved by isotopic enrichment in conjunction with high magnetic field (28.2 T) and fast magic-angle spinning (MAS), enabling the rapid detection of 2H NMR spectra in a few seconds to minutes. Specifically, two-dimensional (2D) 2H–1H CP-iCOSY experiment allows the local structures and through-space interactions in a partially deuterated compounds to be elucidated. In doing so, we compare conventional spin-lock and rotor-echo-short-pulse-irradiation RESPIRATIONCP sequences for acquiring 2D 1H–2H correlation spectra. The RESPIRATIONCP sequence allows the detection of 2D peaks at lower CP contact times (0.1–1 ms) than the conventional CP (0.2–4 ms) sequence. Analysis of partially deuterated L-histidine·HCl·H2O and dopamine.HCl is presented, in which the detection of 2D peaks corresponding to 2H–1H pairs separated by greater than 4 Å distance demonstrates the potential of the presented approach for the characterization of packing interactions. These results are corroborated by NMR crystallography analysis using the Gauge-Including Projector Augmented-Wave (GIPAW) approach.
{"title":"Deuteron-proton isotope correlation spectroscopy at high magnetic fields","authors":"Neethu Thomas , Claire Welton , Tomasz Pawlak , Parth Raval , Julien Trébosc , Sheetal K. Jain , G.N. Manjunatha Reddy","doi":"10.1016/j.ssnmr.2025.101993","DOIUrl":"10.1016/j.ssnmr.2025.101993","url":null,"abstract":"<div><div>A cross-polarization <sup>2</sup>H–<sup>1</sup>H isotope correlation spectroscopy (CP-iCOSY) approach is presented for characterizing a deuterated amino acid, pharmaceutical compound and a solid formulation. This can be achieved by isotopic enrichment in conjunction with high magnetic field (28.2 T) and fast magic-angle spinning (MAS), enabling the rapid detection of <sup>2</sup>H NMR spectra in a few seconds to minutes. Specifically, two-dimensional (2D) <sup>2</sup>H–<sup>1</sup>H CP-iCOSY experiment allows the local structures and through-space interactions in a partially deuterated compounds to be elucidated. In doing so, we compare conventional spin-lock and rotor-echo-short-pulse-irradiation <sup>RESPIRATION</sup>CP sequences for acquiring 2D <sup>1</sup>H–<sup>2</sup>H correlation spectra. The <sup>RESPIRATION</sup>CP sequence allows the detection of 2D peaks at lower CP contact times (0.1–1 ms) than the conventional CP (0.2–4 ms) sequence. Analysis of partially deuterated L-histidine·HCl·H<sub>2</sub>O and dopamine.HCl is presented, in which the detection of 2D peaks corresponding to <sup>2</sup>H–<sup>1</sup>H pairs separated by greater than 4 Å distance demonstrates the potential of the presented approach for the characterization of packing interactions. These results are corroborated by NMR crystallography analysis using the Gauge-Including Projector Augmented-Wave (GIPAW) approach.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"136 ","pages":"Article 101993"},"PeriodicalIF":1.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143418551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.ssnmr.2024.101984
Jan Blahut , Zdeněk Tošner
Exciting developments in new experimental methods for multidimensional solid-state NMR spectroscopy have recently been achieved using optimal-control theory. These results, in turn, have triggered the development of new pulse sequences based on traditional analytical theories. This trend article summarises the key steps leading to these advancements. It also describes additional applications of optimal control beyond structural biology and envisions similar progress in the NMR of solid materials. Despite attractive features of optimal-control pulse sequences demonstrated in the proof-of-concept studies, their experimental utilization remains sparse, probably due to the lack of awareness among experimentalists. We hope this mini-review helps to spread optimal-control methods into routine experimental workflows. Furthermore, we offer a personal outlook on how numerical optimisations could in general enhance the experimental capabilities of solid-state NMR in the near future, with optimal control serving as a pioneer exploring new possibilities.
{"title":"Optimal control: From sensitivity improvement to alternative pulse-sequence design in solid-state NMR","authors":"Jan Blahut , Zdeněk Tošner","doi":"10.1016/j.ssnmr.2024.101984","DOIUrl":"10.1016/j.ssnmr.2024.101984","url":null,"abstract":"<div><div>Exciting developments in new experimental methods for multidimensional solid-state NMR spectroscopy have recently been achieved using optimal-control theory. These results, in turn, have triggered the development of new pulse sequences based on traditional analytical theories. This trend article summarises the key steps leading to these advancements. It also describes additional applications of optimal control beyond structural biology and envisions similar progress in the NMR of solid materials. Despite attractive features of optimal-control pulse sequences demonstrated in the proof-of-concept studies, their experimental utilization remains sparse, probably due to the lack of awareness among experimentalists. We hope this mini-review helps to spread optimal-control methods into routine experimental workflows. Furthermore, we offer a personal outlook on how numerical optimisations could in general enhance the experimental capabilities of solid-state NMR in the near future, with optimal control serving as a pioneer exploring new possibilities.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"135 ","pages":"Article 101984"},"PeriodicalIF":1.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142915579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The naturally abundant 14N isotope (>99 %) is sparingly employed for characterization in solid-state nuclear magnetic resonance (NMR) despite the importance of nitrogen atoms in shaping molecular structures and properties. This inhibition can be attributed to large quadrupolar couplings (∼several MHz), resulting in more involved spin methodologies for 14N nuclei. Experimentally, spin-½ nuclei are utilized for excitation and detection through two-way (1H→14N→1H) polarization transfer between spin-½ nuclei and 14N. Herein, we show direct 14N spin excitation followed by 14N→1H cross-polarization (CP) is an efficient method for polarization transfer even for 14N spins with a large quadrupolar coupling constant (3–4 MHz). This contrasts previous studies, which indicate that 1H-14N spectra can only be observed with a pair of at least a rotor period-long symmetric 14N pulses (J. Chem. Phys. 151 (2019) 154202). The 14N→1H CP spin dynamics have been experimentally established and can be explained in analogy to spin-½ Hartmann-Hahn CP if visualized in the quadrupolar jolting frame. The 14N→1H CP is ∼1.9–2.7 times more efficient in polarization transfer than other 14N edited experiments. Considering shorter 14N T1 relaxation times compared to protons, 14N edited spectra were recorded using 14N→1H CP, resulting in enhanced sensitivity per unit of time.
{"title":"Spin-dynamics and efficiency of single 14N-1H cross-polarization at fast magic angle spinning in solids","authors":"Vipin Agarwal , Sreejith Raran-Kurussi , Yusuke Nishiyama","doi":"10.1016/j.ssnmr.2025.101992","DOIUrl":"10.1016/j.ssnmr.2025.101992","url":null,"abstract":"<div><div>The naturally abundant <sup>14</sup>N isotope (>99 %) is sparingly employed for characterization in solid-state nuclear magnetic resonance (NMR) despite the importance of nitrogen atoms in shaping molecular structures and properties. This inhibition can be attributed to large quadrupolar couplings (∼several MHz), resulting in more involved spin methodologies for <sup>14</sup>N nuclei. Experimentally, spin-½ nuclei are utilized for excitation and detection through two-way (<sup>1</sup>H→<sup>14</sup>N→<sup>1</sup>H) polarization transfer between spin-½ nuclei and <sup>14</sup>N. Herein, we show direct <sup>14</sup>N spin excitation followed by <sup>14</sup>N→<sup>1</sup>H cross-polarization (CP) is an efficient method for polarization transfer even for <sup>14</sup>N spins with a large quadrupolar coupling constant (3–4 MHz). This contrasts previous studies, which indicate that <sup>1</sup>H-<sup>14</sup>N spectra can only be observed with a pair of at least a rotor period-long symmetric <sup>14</sup>N pulses (<em>J. Chem. Phys. 151</em> (2019) <em>154202</em>). The <sup>14</sup>N→<sup>1</sup>H CP spin dynamics have been experimentally established and can be explained in analogy to spin-½ Hartmann-Hahn CP if visualized in the quadrupolar jolting frame. The <sup>14</sup>N→<sup>1</sup>H CP is ∼1.9–2.7 times more efficient in polarization transfer than other <sup>14</sup>N edited experiments. Considering shorter <sup>14</sup>N T<sub>1</sub> relaxation times compared to protons, <sup>14</sup>N edited spectra were recorded using <sup>14</sup>N→<sup>1</sup>H CP, resulting in enhanced sensitivity per unit of time.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"136 ","pages":"Article 101992"},"PeriodicalIF":1.8,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143376888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cellulose–lignin blends are proposed as alternative precursors for carbon fiber (CF) production, offering a potential sustainable and cost-effective alternative to the expensive fossil-based polymers currently used. The characteristics of the precursor fibers including their crystallinity, the incorporated chemical structures and the distribution of the biopolymers have a significant influence on their carbonization behavior and the properties of the CFs. They are partly determined by the composition of the bio-based resources and the conditions used during the fiber fixation, i.e. the coagulation, an important processing step. In this work, 13C solid and 2D solution NMR methodologies were applied to investigate the impact of coagulation and thermostabilization conditions on cellulose and cellulose-lignin blends using a thin film model. Solid state NMR spectroscopy showed that the choice of the anti-solvent influenced the proportion of cellulose II versus amorphous regions in the coagulated films. Independent of the presence of lignin, the choice of anti-solvent seems to impact the rate of thermal reactions. After thermostabilization at 245 °C, the samples were investigated using a solution NMR protocol devised for cellulosic materials. At 275 °C, most of the samples became insoluble for solution NMR. However, solid state NMR revealed further changes in the chemical composition, which were dependent on both the presence of lignin and the choice of anti-solvent. This multi-faceted approach combining solid state and 2D solution NMR techniques provides a comprehensive understanding of the cellulose structure and the products formed for cellulose-lignin-based CFs, which is crucial for optimizing their properties and potential applications.
纤维素-木质素混合物被提议作为碳纤维（CF）生产的替代前体，为目前使用的昂贵化石基聚合物提供了一种潜在的可持续且具有成本效益的替代品。前体纤维的特性，包括其结晶度、结合的化学结构和生物聚合物的分布，对其碳化行为和碳纤维的特性有重大影响。它们在一定程度上取决于生物基资源的成分以及纤维固定（即凝固）过程中使用的条件，凝固是一个重要的加工步骤。在这项工作中，采用了 13C 固态和二维溶液 NMR 方法，利用薄膜模型研究了凝固和热稳定条件对纤维素和纤维素-木质素混合物的影响。固态核磁共振光谱显示，反溶剂的选择会影响凝固薄膜中纤维素 II 与无定形区域的比例。与木质素的存在无关，反溶剂的选择似乎会影响热反应的速度。在 245 °C 下进行热稳定后，使用针对纤维素材料设计的溶液 NMR 方案对样品进行了研究。在 275 °C 时，大多数样品变得不溶于溶液 NMR。然而，固态 NMR 揭示了化学成分的进一步变化，这些变化取决于木质素的存在和反溶剂的选择。这种将固态和二维溶液 NMR 技术相结合的多层面方法提供了对纤维素结构以及纤维素-木质素基 CF 所形成产物的全面了解，这对于优化其性能和潜在应用至关重要。
{"title":"Applications of NMR based methodologies investigating the behavior of lignin and cellulose towards bio-based carbon fibers production","authors":"Feryal Guerroudj , Lukas Fliri , Jenny Bengtsson , Leandro Cid Gomes , Tristan Gazzola , Michael Hummel , Diana Bernin","doi":"10.1016/j.ssnmr.2024.101977","DOIUrl":"10.1016/j.ssnmr.2024.101977","url":null,"abstract":"<div><div>Cellulose–lignin blends are proposed as alternative precursors for carbon fiber (CF) production, offering a potential sustainable and cost-effective alternative to the expensive fossil-based polymers currently used. The characteristics of the precursor fibers including their crystallinity, the incorporated chemical structures and the distribution of the biopolymers have a significant influence on their carbonization behavior and the properties of the CFs. They are partly determined by the composition of the bio-based resources and the conditions used during the fiber fixation, i.e. the coagulation, an important processing step. In this work, <sup>13</sup>C solid and 2D solution NMR methodologies were applied to investigate the impact of coagulation and thermostabilization conditions on cellulose and cellulose-lignin blends using a thin film model. Solid state NMR spectroscopy showed that the choice of the anti-solvent influenced the proportion of cellulose II <em>versus</em> amorphous regions in the coagulated films. Independent of the presence of lignin, the choice of anti-solvent seems to impact the rate of thermal reactions. After thermostabilization at 245 °C, the samples were investigated using a solution NMR protocol devised for cellulosic materials. At 275 °C, most of the samples became insoluble for solution NMR. However, solid state NMR revealed further changes in the chemical composition, which were dependent on both the presence of lignin and the choice of anti-solvent. This multi-faceted approach combining solid state and 2D solution NMR techniques provides a comprehensive understanding of the cellulose structure and the products formed for cellulose-lignin-based CFs, which is crucial for optimizing their properties and potential applications.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"134 ","pages":"Article 101977"},"PeriodicalIF":1.8,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-20DOI: 10.1016/j.ssnmr.2024.101976
Liliya Vugmeyster , Riqiang Fu , Dmitry Ostrovsky
17O NMR methods are emerging as a powerful tool for determination of structure and dynamics in materials and biological solids. We present experimental and theoretical frameworks for measurements of 17O NMR relaxation times in static solids focusing on the excitation of the central transition of the 17O spin 5/2 system. We employ 17O-enriched NaNO3 as a model compound, in which the nitrate oxygen atoms undergo 3-fold jumps. Rotating frame (), transverse () and longitudinal () relaxation times as well as line shapes were measured for the central transition in the 280 to 195 K temperature range at 14.1 and 18.8 T field strengths. We conduct experimental and theoretical comparison between different relaxation methods and demonstrate the advantage of combining data from multiple relaxation time and line shape measurements to obtain a more accurate determination of the dynamics as compared to either of the techniques alone. The computational framework for relaxation of spin 5/2 nuclei is developed using the numerical integration of the Liouville − von Neumann equation.
{"title":"17O NMR relaxation measurements for investigation of molecular dynamics in static solids using sodium nitrate as a model compound","authors":"Liliya Vugmeyster , Riqiang Fu , Dmitry Ostrovsky","doi":"10.1016/j.ssnmr.2024.101976","DOIUrl":"10.1016/j.ssnmr.2024.101976","url":null,"abstract":"<div><div><sup>17</sup>O NMR methods are emerging as a powerful tool for determination of structure and dynamics in materials and biological solids. We present experimental and theoretical frameworks for measurements of <sup>17</sup>O NMR relaxation times in static solids focusing on the excitation of the central transition of the <sup>17</sup>O spin 5/2 system. We employ <sup>17</sup>O-enriched NaNO<sub>3</sub> as a model compound, in which the nitrate oxygen atoms undergo 3-fold jumps. Rotating frame (<span><math><mrow><msub><mi>T</mi><mrow><mn>1</mn><mi>ρ</mi></mrow></msub></mrow></math></span>), transverse (<span><math><mrow><msub><mi>T</mi><mn>2</mn></msub></mrow></math></span>) and longitudinal (<span><math><mrow><msub><mi>T</mi><mn>1</mn></msub></mrow></math></span>) relaxation times as well as line shapes were measured for the central transition in the 280 to 195 K temperature range at 14.1 and 18.8 T field strengths. We conduct experimental and theoretical comparison between different relaxation methods and demonstrate the advantage of combining data from multiple relaxation time and line shape measurements to obtain a more accurate determination of the dynamics as compared to either of the techniques alone. The computational framework for relaxation of spin 5/2 nuclei is developed using the numerical integration of the Liouville − von Neumann equation.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"134 ","pages":"Article 101976"},"PeriodicalIF":1.8,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-25DOI: 10.1016/j.ssnmr.2024.101975
Kathy Duong , Evan Moss , Courtney Reichhardt
People with the genetic disease cystic fibrosis (CF) often have chronic airway infections and produce airway secretions called sputum. A better understanding of sputum composition is desired in order to track changes in response to CF therapeutics and to improve laboratory models for the study of CF airway infections. The glycosylated protein mucin is a primary component. Along with extracellular DNA, mucin gives rise to the high viscoelasticity of sputum, which inhibits airway clearance and is thought to promote chronic airway infections in people with CF. Past studies of sputum composition identified additional biomolecular components of sputum including other proteins, both glycosylated and not glycosylated, free amino acids, and lipids. Typically, studies of sputum, as well as other complex biological materials, have focused on soluble or isolated components. Solid-state NMR is not limited to the study of soluble components. Instead, it can provide molecular-level information about insoluble biological samples. Additionally, solid-state NMR can provide information about sample composition without requiring any processing of the sample, eliminating the possibility of misestimating certain components due to insolubility or potential sample loss in isolation steps. In this study, we used both 13C and 31P CPMAS to investigate the total composition of sputum samples obtained from six people with CF. We compared these spectra to those of commercially available mucin, DNA, and phospholipid samples. Lastly, we performed complementary biochemical analyses to identify specific proteins present in the sputum samples. Overall, our findings provide insight into the composition of unprocessed sputum samples from people with CF, which can be used as a benchmark for future investigations of CF and infections in the airways of people with CF. Further, this study provides opportunities to expand the solid-state NMR approach to include dynamic nuclear polarization (DNP) to obtain high-resolution information of sputum and similar biological samples that are not feasible to isotopically enrich.
{"title":"Solid-state NMR compositional analysis of sputum from people with cystic fibrosis","authors":"Kathy Duong , Evan Moss , Courtney Reichhardt","doi":"10.1016/j.ssnmr.2024.101975","DOIUrl":"10.1016/j.ssnmr.2024.101975","url":null,"abstract":"<div><div>People with the genetic disease cystic fibrosis (CF) often have chronic airway infections and produce airway secretions called sputum. A better understanding of sputum composition is desired in order to track changes in response to CF therapeutics and to improve laboratory models for the study of CF airway infections. The glycosylated protein mucin is a primary component. Along with extracellular DNA, mucin gives rise to the high viscoelasticity of sputum, which inhibits airway clearance and is thought to promote chronic airway infections in people with CF. Past studies of sputum composition identified additional biomolecular components of sputum including other proteins, both glycosylated and not glycosylated, free amino acids, and lipids. Typically, studies of sputum, as well as other complex biological materials, have focused on soluble or isolated components. Solid-state NMR is not limited to the study of soluble components. Instead, it can provide molecular-level information about insoluble biological samples. Additionally, solid-state NMR can provide information about sample composition without requiring any processing of the sample, eliminating the possibility of misestimating certain components due to insolubility or potential sample loss in isolation steps. In this study, we used both <sup>13</sup>C and <sup>31</sup>P CPMAS to investigate the total composition of sputum samples obtained from six people with CF. We compared these spectra to those of commercially available mucin, DNA, and phospholipid samples. Lastly, we performed complementary biochemical analyses to identify specific proteins present in the sputum samples. Overall, our findings provide insight into the composition of unprocessed sputum samples from people with CF, which can be used as a benchmark for future investigations of CF and infections in the airways of people with CF. Further, this study provides opportunities to expand the solid-state NMR approach to include dynamic nuclear polarization (DNP) to obtain high-resolution information of sputum and similar biological samples that are not feasible to isotopically enrich.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"134 ","pages":"Article 101975"},"PeriodicalIF":1.8,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142569403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-14DOI: 10.1016/j.ssnmr.2024.101974
Christine Chrissian , Michael L. Stawski , Andrew P. Williams , Ruth E. Stark
Among the many natural biomaterials for which information on atomic-level structure and reorientational motion can offer essential clues to function, insoluble multi-component composites with limited degrees of order are among the most challenging to study. Despite its limited sensitivity, solid-state NMR (ssNMR) is often the technique of choice to ferret out these details in carbon- and nitrogen-rich materials: this spectroscopic approach can probe many biomaterials in their native or near-native states, either with or without the introduction of stable NMR-active isotopes, or with the assistance of dynamic nuclear polarization technology. During a span of close to four decades, such research targets and ssNMR approaches have been exemplified by insects, a diverse and evolutionarily agile group of organisms with global impacts that include ecology, agriculture, and human disease. In this short review, we present case studies on insect cuticles that range from protective exoskeletons and egg capsules to the wing structures that enable flight and showcase nature's awe-inspiring beauty, highlighting the use of ssNMR spectroscopy to profile chemical composition, elucidate macromolecular architecture, and monitor metabolic development in these fascinating biological assemblies.
{"title":"Elucidating structure and metabolism of insect biomaterials by solid-state NMR","authors":"Christine Chrissian , Michael L. Stawski , Andrew P. Williams , Ruth E. Stark","doi":"10.1016/j.ssnmr.2024.101974","DOIUrl":"10.1016/j.ssnmr.2024.101974","url":null,"abstract":"<div><div>Among the many natural biomaterials for which information on atomic-level structure and reorientational motion can offer essential clues to function, insoluble multi-component composites with limited degrees of order are among the most challenging to study. Despite its limited sensitivity, solid-state NMR (ssNMR) is often the technique of choice to ferret out these details in carbon- and nitrogen-rich materials: this spectroscopic approach can probe many biomaterials in their native or near-native states, either with or without the introduction of stable NMR-active isotopes, or with the assistance of dynamic nuclear polarization technology. During a span of close to four decades, such research targets and ssNMR approaches have been exemplified by insects, a diverse and evolutionarily agile group of organisms with global impacts that include ecology, agriculture, and human disease. In this short review, we present case studies on insect cuticles that range from protective exoskeletons and egg capsules to the wing structures that enable flight and showcase nature's awe-inspiring beauty, highlighting the use of ssNMR spectroscopy to profile chemical composition, elucidate macromolecular architecture, and monitor metabolic development in these fascinating biological assemblies.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"134 ","pages":"Article 101974"},"PeriodicalIF":1.8,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142508285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1016/j.ssnmr.2024.101973
Shichen Yuan , Avery Brown , Zhaoxi Zheng , Robert L. Johnson , Karen Agro , Andrea Kruse , Michael T. Timko , Klaus Schmidt-Rohr
The molecular structure of hydrochars produced from 13C-enriched glucose under various conditions has been elucidated based on advanced one- and two-dimensional (2D) 1H-13C and 13C–13C solid-state nuclear magnetic resonance (NMR) with spectral editing. Regardless of synthesis conditions, hydrochars consist mostly of oxygen-substituted arene rings (including diphenols) and furans connected by alkyl linkers rich in ketones. Cross-linking nonprotonated and methyne (C-H) alkyl carbons have been identified through spectrally edited 2D NMR. Alkenes and ‘quaternary’ C-O are observed only at low synthesis temperature, while some clusters of fused arene rings are generated at high temperature. Hydrochar composition is nearly independent of reaction time in the range from 1 to 5 h. Equilibration of 13C magnetization within 1 s shows that the materials are homogeneous on the 5-nm scale, refuting core–shell models of hydrochar microspheres. While furan C-O carbons bonded to alkyl groups or ketones show distinctive cross peaks in 2D NMR, phenolic C-OH is observed unambiguously by hydroxyl-proton selection. While methylene-linked furan rings are fairly common, the signal previously assigned to furan Cα-Cα linkages is shown to arise from abundant, stable catecholic ortho-diphenols, whose HO-C=C-OH structure is proved by 2D13C–13C NMR after hydroxyl-proton selection. Quantitative 13C NMR spectra of low- and high-temperature hydrochars have been matched by chemical-shift simulations for representative structural models. Mixed phenol and furan rings connected by ketones and alkyl linkers provide good fits of the experimental spectra, while literature models dominated by large clusters of fused rings and with few phenols or alkyl-linked ketones do not.
{"title":"Glucose hydrochar consists of linked phenol, furan, arene, alkyl, and ketone structures revealed by advanced solid-state nuclear magnetic resonance","authors":"Shichen Yuan , Avery Brown , Zhaoxi Zheng , Robert L. Johnson , Karen Agro , Andrea Kruse , Michael T. Timko , Klaus Schmidt-Rohr","doi":"10.1016/j.ssnmr.2024.101973","DOIUrl":"10.1016/j.ssnmr.2024.101973","url":null,"abstract":"<div><div>The molecular structure of hydrochars produced from <sup>13</sup>C-enriched glucose under various conditions has been elucidated based on advanced one- and two-dimensional (2D) <sup>1</sup>H-<sup>13</sup>C and <sup>13</sup>C–<sup>13</sup>C solid-state nuclear magnetic resonance (NMR) with spectral editing. Regardless of synthesis conditions, hydrochars consist mostly of oxygen-substituted arene rings (including diphenols) and furans connected by alkyl linkers rich in ketones. Cross-linking nonprotonated and methyne (C-H) alkyl carbons have been identified through spectrally edited 2D NMR. Alkenes and ‘quaternary’ C-O are observed only at low synthesis temperature, while some clusters of fused arene rings are generated at high temperature. Hydrochar composition is nearly independent of reaction time in the range from 1 to 5 h. Equilibration of <sup>13</sup>C magnetization within 1 s shows that the materials are homogeneous on the 5-nm scale, refuting core–shell models of hydrochar microspheres. While furan C-O carbons bonded to alkyl groups or ketones show distinctive cross peaks in 2D NMR, phenolic C-OH is observed unambiguously by hydroxyl-proton selection. While methylene-linked furan rings are fairly common, the signal previously assigned to furan Cα-Cα linkages is shown to arise from abundant, stable catecholic <em>ortho</em>-diphenols, whose HO-C=C-OH structure is proved by 2D<sup>13</sup>C–<sup>13</sup>C NMR after hydroxyl-proton selection. Quantitative <sup>13</sup>C NMR spectra of low- and high-temperature hydrochars have been matched by chemical-shift simulations for representative structural models. Mixed phenol and furan rings connected by ketones and alkyl linkers provide good fits of the experimental spectra, while literature models dominated by large clusters of fused rings and with few phenols or alkyl-linked ketones do not.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"134 ","pages":"Article 101973"},"PeriodicalIF":1.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-21DOI: 10.1016/j.ssnmr.2024.101972
Barbara Perrone , Maria Gunnarsson , Diana Bernin , Emma Sparr , Daniel Topgaard
Solid-state NMR has great potential for investigating molecular structure, dynamics, and organization of the stratum corneum, the outer 10–20 μm of the skin, but is hampered by the unfeasibility of isotope labelling as generally required to reach sufficient signal-to-noise ratio for the more informative multidimensional NMR techniques. In this preliminary study of pig stratum corneum at 35 °C and water-free conditions, we demonstrate that cryogenic probe technology offers sufficient signal boost to observe previously undetectable minor resonances that can be uniquely assigned to fluid cholesterol, ceramides, and triacylglycerols, as well as enables 1H–1H spin diffusion monitored by 2D 1H-13C HETCOR to estimate 1–100 nm distances between specific atomic sites on proteins and lipids. The new capabilities open up for future multidimensional solid-state NMR studies to answer long-standing questions about partitioning of additives, such as pharmaceutically active substances, between solid and liquid domains within the protein and lipid phases in the stratum corneum and the lipids of the sebum.
{"title":"Cryogenic probe technology enables multidimensional solid-state NMR of the stratum corneum without isotope labeling","authors":"Barbara Perrone , Maria Gunnarsson , Diana Bernin , Emma Sparr , Daniel Topgaard","doi":"10.1016/j.ssnmr.2024.101972","DOIUrl":"10.1016/j.ssnmr.2024.101972","url":null,"abstract":"<div><div>Solid-state NMR has great potential for investigating molecular structure, dynamics, and organization of the <em>stratum corneum</em>, the outer 10–20 μm of the skin, but is hampered by the unfeasibility of isotope labelling as generally required to reach sufficient signal-to-noise ratio for the more informative multidimensional NMR techniques. In this preliminary study of pig <em>stratum corneum</em> at 35 °C and water-free conditions, we demonstrate that cryogenic probe technology offers sufficient signal boost to observe previously undetectable minor resonances that can be uniquely assigned to fluid cholesterol, ceramides, and triacylglycerols, as well as enables <sup>1</sup>H–<sup>1</sup>H spin diffusion monitored by 2D <sup>1</sup>H-<sup>13</sup>C HETCOR to estimate 1–100 nm distances between specific atomic sites on proteins and lipids. The new capabilities open up for future multidimensional solid-state NMR studies to answer long-standing questions about partitioning of additives, such as pharmaceutically active substances, between solid and liquid domains within the protein and lipid phases in the <em>stratum corneum</em> and the lipids of the sebum.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"134 ","pages":"Article 101972"},"PeriodicalIF":1.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a high-resolution magic-angle spinning (MAS) solid-state NMR (ssNMR) study to characterize nontuberculous mycobacteria (NTM). We studied two different NTM strains, Mycobacterium smegmatis, a model, non-pathogenic strain, and Mycobacterium abscessus, an emerging and important human pathogen. Hydrated NTM samples were studied at natural abundance without isotope-labelling, as whole-cells versus cell envelope isolates, and native versus fixed sample preparations. We utilized 1D13C and 2D 1H-13C ssNMR spectra and peak deconvolution to identify NTM cell-wall chemical sites. More than ∼100 distinct 13C signals were identified in the ssNMR spectra. We provide tentative assignments for ∼30 polysaccharides by using well resolved 1H/13C chemical shifts from the 2D INEPT-based 1H-13C ssNMR spectrum. The signals originating from both the flexible and rigid fractions of the whole-cell bacteria samples were selectively analyzed by utilizing either CP or INEPT based 13C ssNMR spectra. CP buildup curves provide insights into the dynamical similarity of the cell-wall components for NTM strains. Signals from peptidoglycan, arabinogalactan and mycolic acid were identified. The majority of the 13C signals were not affected by fixation of the whole cell samples. The isolated cell envelope NMR spectrum overlap with the whole-cell spectrum to a large extent, where the latter has more signals. As an orthogonal way of characterizing these bacteria, electron microscopy (EM) was used to provide spatial information. ssNMR and EM data suggest that the M. abscessus cell-wall is composed of a smaller peptidoglycan layer which is more flexible compared to M. smegmatis, which may be related to its higher pathogenicity. Here in this work, we used high-resolution 2D ssNMR first time to characterize NTM strains and identify chemical sites. These results will aid the development of structure-based approaches to combat NTM infections.
{"title":"High-resolution 2D solid-state NMR provides insights into nontuberculous mycobacteria","authors":"Chang-Hyeock Byeon , Kasper Holst Hansen , William DePas , Ümit Akbey","doi":"10.1016/j.ssnmr.2024.101970","DOIUrl":"10.1016/j.ssnmr.2024.101970","url":null,"abstract":"<div><div>We present a high-resolution magic-angle spinning (MAS) solid-state NMR (ssNMR) study to characterize nontuberculous mycobacteria (NTM). We studied two different NTM strains, <em>Mycobacterium smegmatis</em>, a model, non-pathogenic strain, and <em>Mycobacterium abscessus</em>, an emerging and important human pathogen. Hydrated NTM samples were studied at natural abundance without isotope-labelling, as whole-cells versus cell envelope isolates, and native versus fixed sample preparations. We utilized 1D<sup>13</sup>C and 2D <sup>1</sup>H-<sup>13</sup>C ssNMR spectra and peak deconvolution to identify NTM cell-wall chemical sites. More than ∼100 distinct <sup>13</sup>C signals were identified in the ssNMR spectra. We provide tentative assignments for ∼30 polysaccharides by using well resolved <sup>1</sup>H/<sup>13</sup>C chemical shifts from the 2D INEPT-based <sup>1</sup>H-<sup>13</sup>C ssNMR spectrum. The signals originating from both the flexible and rigid fractions of the whole-cell bacteria samples were selectively analyzed by utilizing either CP or INEPT based <sup>13</sup>C ssNMR spectra. CP buildup curves provide insights into the dynamical similarity of the cell-wall components for NTM strains. Signals from peptidoglycan, arabinogalactan and mycolic acid were identified. The majority of the <sup>13</sup>C signals were not affected by fixation of the whole cell samples. The isolated cell envelope NMR spectrum overlap with the whole-cell spectrum to a large extent, where the latter has more signals. As an orthogonal way of characterizing these bacteria, electron microscopy (EM) was used to provide spatial information. ssNMR and EM data suggest that the <em>M. abscessus</em> cell-wall is composed of a smaller peptidoglycan layer which is more flexible compared to <em>M. smegmatis</em>, which may be related to its higher pathogenicity. Here in this work, we used high-resolution 2D ssNMR first time to characterize NTM strains and identify chemical sites. These results will aid the development of structure-based approaches to combat NTM infections.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"134 ","pages":"Article 101970"},"PeriodicalIF":1.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142308575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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