Name: Vídeo: 15N-Heteronuclear Single Quantum Coherence (HSQC) Titration Experiments to Monitor the Chemical Shifts of the 1H and 15N NMR Resonances
Uploaded: 2024-05-17T14:25:00
Duration: 2 min
Description: 293 visualizações. 15N-Heteronuclear Single Quantum Coherence (HSQC) Titration Experiments to Monitor the Chemical Shifts of the 1H and 15N NMR Resonances

15n-heteronuclear single quantum coherence (hsqc) titration experiments to monitor the chemical shifts of the 1h and 15n nmr resonances

Técnicas avançadas de RMN para análise de interação glicano-proteína

Molecular recognition of glycans is essential for many processes related to health and disease. The specificity and selectivity of biological receptors (lectins, antibodies, enzymes) for glycans heavily depend on adjusting the precarious balance between the diverse components of enthalpy (CH-&#960; and van der Waals, hydrogen bonds, electrostatics) and entropy (hydrophobicity, dynamics, solvation-desolvation)1.
Given the large chemical diversity and dynamic nature of glycans, NMR methods have been widely employed to dissect glycan interactions for more than 25 years2, since these methodologies afford superb information on molecular recognition events with precise details, at atomic resolution3,4, even when the required interaction evidence cannot be retrieved by employing other methodologies. As key point, NMR is versatile and allows studying dynamic events, at the atomic level, at different time scales, constituting the best technique by far for studying the structure, conformation, and dynamics of glycans in solution. Nevertheless, disentangling this information may be a rather complex process that requires the employment of well-defined strategies together with careful data analysis5.
NMR techniques are diverse and, indeed, there are many methodologies that can be employed to unravel glycan-protein interactions6. We herein describe two basic NMR approaches that are currently employed to decipher glycan-receptor interactions7,8, making emphasis on how to untangle the presentation of the key glycan epitope as well as the protein binding site9.
In any molecular recognition event, when a receptor binds to a given ligand, there is a chemical exchange process that affects many NMR parameters of the participants in the binding10. Therefore, from the NMR perspective, the interaction can be monitored either from the point of view of the glycan ligand or from that of the protein receptor11. Generally speaking, the protein receptor is a large biomolecule (slow rotational motion, with rates in the ns timescale, and therefore, fast transverse relaxation), while the interacting glycan can be considered as a small-medium size molecule (fast rotational motion, with rates in the ps timescale, and slow transverse relaxation)12. From a standard perspective, the NMR signals of the glycan are narrow, while those of the receptor are broad13.
Ligand-based NMR methods rely on the dramatic change that many glycan NMR parameters experience when passing from the free to the bound state14. STD-NMR is the most employed experimental NMR technique to assess diverse glycan binding features15, from deducing the existence of binding in the solution state to the determination of the glycan binding epitope; that is, the atoms of the ligand that are in contact with the protein receptor16.
Alternatively, receptor-based NMR methods monitor the changes that take place in the signals of the protein receptor in the presence of the glycan with respect to those recorded for the apo state17. These are mainly focused on screening the chemical shift perturbations of the protein signals between both states. The most commonly employed experiment is 1H-15N HSQC, or its TROSY alternatives18.
The combination of both approaches allows applying NMR to many diverse systems that display a wide range of affinities. However, for the receptor-based NMR methods, in contrast to those based on the ligand, a relatively large amount of soluble, non-aggregated, stable isotope-labelled (15N) protein must be available.
We herein describe both methods, highlighting their strengths, and weaknesses. Note that the basic steps described in the protocol serve as examples for the use of Bruker spectrometers. Consequently, commands and parameters names align with those utilized in TopSpin (Bruker&#39;s spectrometers control software).

Autor em destaque: Revelando os aspectos estruturais e dinâmicos do reconhecimento molecular de glicanos

Desembaraçando as interações glicano-proteína: ressonância magnética nuclear (RMN) para o resgate

15N-Heteronuclear Single Quantum Coherence (HSQC) Titration Experiments to Monitor the Chemical Shifts of the 1H and 15N NMR Resonances

15n-heteronuclear-single-quantum-coherence-hsqc-titration-experiments

Research

JoVE Journal

Chemistry

293 visualizações. 15N-Heteronuclear Single Quantum Coherence (HSQC) Titration Experiments to Monitor the Chemical Shifts of the 1H and 15N NMR Resonances

Vídeo: 15N-Heteronuclear Single Quantum Coherence (HSQC) Titration Experiments to Monitor the Chemical Shifts of the  1H and  15N NMR Resonances

Disentangling Glycan-Protein Interactions: Nuclear Magnetic Resonance (NMR) to the Rescue

The interactions of glycans with proteins modulate many events related to health and disease. In fact, the establishment of these recognition events and their biological consequences are intimately related to the three-dimensional structures of both partners, as well as to their dynamic features and their presentation on the corresponding cell compartments. NMR techniques are unique to disentangle these characteristics and, indeed, diverse NMR-based methodologies have been developed and applied to monitor the binding events of glycans with their associate receptors. This protocol outlines the procedures to acquire, process and analyze two of the most powerful NMR methodologies employed in the NMR-glycobiology field, 1H-Saturation transfer difference (STD) and 1H,15N-Heteronuclear single quantum coherence (HSQC) titration experiments, which complementarily offer information from the glycan and protein perspective, respectively. Indeed, when combined they offer a powerful toolkit for elucidating both the structural and dynamic aspects of molecular recognition processes. This comprehensive approach enhances our understanding of glycan-protein interactions and contributes to advancing research in the chemical glycobiology field.

Here, we present a protocol detailing the acquisition, processing, and analysis of a series of NMR experiments aimed at characterizing protein-glycan interactions in solution. Most common ligand-based and protein-based methodologies are outlined, which undoubtedly contribute to the fields of structural glycobiology and molecular recognition studies.

The interactions of glycans with proteins modulate many events related to health and disease. In fact, the establishment of these recognition events and ...

Química

Acquisition, Processing, and Analysis of 1H-Saturation Transfer Difference (STD) NMR to Characterize Protein-Glycan Interactions

Aquisição, processamento e análise de RMN de diferençade transferência de 1 saturação de H (STD) para caracterizar as interações proteína-glicano