INEPT and CP transfer efficiencies of dynamic systems in MAS solid-state NMR

Aebischer, Kathrin; Ernst, Matthias

doi:10.1016/j.jmr.2024.107617

Cited by 13 publications

(10 citation statements)

References 43 publications

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“…To inspect the effect of hydration on the structure and dynamics of the film, we also recorded INEPT-transferbased HSQC experiments, where only those resonances emerge that have long coherence lifetimes due to motioninduced dipolar decoupling. 91 This divergence implies that the hard segments of the repetitive units of N16C go through a major structural rearrangement when the water-solubilized form assembles into a solid film, while the structure of the glycine-rich soft segments remains similar in the solubilized and solidified states.…”

Section: ■ Resultsmentioning

confidence: 99%

“…To inspect the effect of hydration on the structure and dynamics of the film, we also recorded INEPT-transfer-based HSQC experiments, where only those resonances emerge that have long coherence lifetimes due to motion-induced dipolar decoupling. 91 Figure 4 D,E displays the overlay of the solid-state CP-based (blue), the solid-state INEPT-based (green), and two solution-state HMQC 1 H– 15 N correlation spectra, one recorded in H 2 O (magenta) and the other one in DMSO- d 6 (orange), and Figure 5 shows the corresponding overlay of the 1 H– 13 C CP-based (HCH in gray) and INEPT-based (HSQC in purple) spectra (the overlay of the solid-state and solution-state 1 H– 13 C HSQC and HMQC spectra is displayed in Figure S5 ). Clearly, the INEPT-based aqueous solution- and solid-state spectra match each other, indicating that there is some solubilized, highly flexible N16C present in the hydrated film sample.…”

Section: Resultsmentioning

confidence: 99%

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Unveiling the Dynamic Self-Assembly of a Recombinant Dragline-Silk-Mimicking Protein

Wu,

Koscic,

Schneider

et al. 2024

Biomacromolecules

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Despite the considerable interest in the recombinant production of synthetic spider silk fibers that possess mechanical properties similar to those of native spider silks, such as the costeffectiveness, tunability, and scalability realization, is still lacking. To address this long-standing challenge, we have constructed an artificial spider silk gene using Golden Gate assembly for the recombinant bacterial production of dragline-mimicking silk, incorporating all the essential components: the N-terminal domain, a 33-residue-long majorampullate-spidroin-inspired segment repeated 16 times, and the Cterminal domain (N16C). This designed silk-like protein was successfully expressed in Escherichia coli, purified, and cast into films from formic acid. We produced uniformly 13 C− 15 N-labeled N16C films and employed solid-state magic-angle spinning nuclear magnetic resonance (NMR) for characterization. Thus, we could demonstrate that our bioengineered silk-like protein self-assembles into a film where, when hydrated, the solvent-exposed layer of the rigid, β-nanocrystalline polyalanine core undergoes a transition to an αhelical structure, gaining mobility to the extent that it fully dissolves in water and transforms into a highly dynamic random coil. This hydration-induced behavior induces chain dynamics in the glycine-rich amorphous soft segments on the microsecond time scale, contributing to the elasticity of the solid material. Our findings not only reveal the presence of structurally and dynamically distinct segments within the film's superstructure but also highlight the complexity of the self-organization responsible for the exceptional mechanical properties observed in proteins that mimic dragline silk.

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Section: ■ Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Unveiling the Dynamic Self-Assembly of a Recombinant Dragline-Silk-Mimicking Protein

Wu,

Koscic,

Schneider

et al. 2024

Biomacromolecules

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“…This observation suggests that the molecular building blocks in expanded H C OF-104 undergo motions on time scales with frequencies of at least tens of kHz, thereby resulting in ineffective 1 H− 13 C CP because of the averaging of the 1 H− 13 C dipolar couplings. 50 Hence, the 13 C NMR spectrum of expanded H C OF-104 was obtained with a direct excitation 13 C spin echo pulse sequence. Consistent with the presence of fast motion of the framework building blocks, the 13 C NMR spectrum of expanded H C OFs displayed sharp, well-resolved 13 C NMR signals (Figure 5d, middle).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…We attempted 1 H– 13 C CPMAS experiments with a contact time of 3 ms and could not observe any signal after acquisition of more than 10 000 scans. This observation suggests that the molecular building blocks in expanded H C OF-104 undergo motions on time scales with frequencies of at least tens of kHz, thereby resulting in ineffective 1 H– 13 C CP because of the averaging of the 1 H– 13 C dipolar couplings . Hence, the 13 C NMR spectrum of expanded H C OF-104 was obtained with a direct excitation 13 C spin echo pulse sequence.…”

Section: Resultsmentioning

confidence: 99%

Ultradynamic Isoreticularly Expanded Porous Organic Crystals

Zhang,

Liang,

Atterberry

et al. 2024

J. Am. Chem. Soc.

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Porous organic materials showcasing large framework dynamics present new paths for adsorption and separation with enhanced capacity and selectivity beyond the size-sieving limits, which is attributed to their guest-responsive sorption behaviors. Porous hydrogen-bonded crosslinked organic frameworks (H C OFs) are attractive for their remarkable ability to undergo guesttriggered expansion and contraction facilitated by their flexible covalent crosslinkages. However, the voids of H C OFs remain limited, which restrains the extent of the framework dynamics. In this work, we synthesized a series of H C OFs characterized by unprecedented size expansion capabilities induced by solvents. These H C OFs were constructed by isoreticularly co-crystallizing two complementary sets of hydrogen bonding building blocks to generate porous molecular crystals, which were crosslinked through thiol−ene/yne single-crystal-to-single-crystal transformations. The generated H C OFs exhibit enhanced chemical durability, high crystallinity, and extraordinary framework dynamics. For instance, H C OF-104 crystals featuring a pore diameter of 13.6 Å expanded in DMF to 300 ± 10% of their original lengths within just 1 min. This expansion allows the H C OFs to adsorb guest molecules that are significantly larger than the pore sizes of their crystalline states. Through methanol-induced contraction, these large guests were encapsulated in the fast-contracted H C OFs. These advancements in porous framework dynamics pave the way for new methods of encapsulating guests for targeted delivery.

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“…For solid protein samples, homonuclear carbon transfer can be achieved either via the dipolar coupling (~2 kHz), or the J-coupling . Theoretically, J-coupling-based transfer can provide 100% transfer efficiency [28][29][30][31][32][33] and they are competitive for samples exhibiting long relaxation times. On the other hand, transfer based on the stronger dipolar coupling can be accomplished in a shorter time, and are logically competitive when shorter relaxation time becomes a limiting factor.…”

Section: Toc Graphicmentioning

confidence: 99%

Homonuclear Simplified Preservation of Equivalent Pathways Spectroscopy

Nimerovsky,

Kosteletos,

Lange

et al. 2024

Preprint

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Recently developed homonuclear Transverse mixing Optimal control Pulses (hTROP) revealed an elegant way to enhance the detected signal in multi-dimensional magic-angle spinning (MAS) NMR experiments. Inspired by their work, we present two homonuclear simplified preservation of equivalent pathways spectroscopy (hSPEPS) sequences for recoupling CA-CO and CA-CB dipolar couplings under fast and ultra-fast MAS rates, theoretically enabling a √2 improvement in sensitivity for each indirect dimension. The efficiencies of hSPEPS is evaluated for non-deuterated samples of influenza A M2 and bacterial rhomboid protease GlpG under two different external magnetic fields (600 MHz and 1200 MHz) and MAS rates (55 kHz and 100 kHz). 3D (H)CA(CO)NH, 3D (H)CO(CA)NH and 3D (H)CB(CA)NH spectra demonstrate the high robustness of hSPEPS elements to excite carbon-carbon correlations, especially in the (H)CB(CA)NH spectrum, where hSPEPS outperforms the J-based sequence by a factor of, on average, 2.85.

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INEPT and CP transfer efficiencies of dynamic systems in MAS solid-state NMR

Cited by 13 publications

References 43 publications

Unveiling the Dynamic Self-Assembly of a Recombinant Dragline-Silk-Mimicking Protein

Unveiling the Dynamic Self-Assembly of a Recombinant Dragline-Silk-Mimicking Protein

Ultradynamic Isoreticularly Expanded Porous Organic Crystals

Homonuclear Simplified Preservation of Equivalent Pathways Spectroscopy

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