{"title":"Estimating cross-relaxation rates between methyl and neighboring labile proton spins in high molecular weight proteins.","authors":"Vitali Tugarinov, G Marius Clore","doi":"10.1007/s10858-025-00469-8","DOIUrl":null,"url":null,"abstract":"<p><p>We show that water saturation leads to deleterious losses in sensitivity of methyl signals in selectively methyl-[<sup>13</sup>CH<sub>3</sub>]-labeled protein samples of high molecular weight proteins dissolved in H<sub>2</sub>O. These losses arise from efficient cross-relaxation between methyl protons and proximal labile protons in the protein structure. A phenomenological model for analysis of methyl intensity decay profiles that involves exchange saturation transfer of magnetization from localized proton spins of water to various labile groups in the protein structure that, in turn, efficiently cross-relax with protons of methyl groups, is described. Analysis of methyl intensity decay profiles with this model allows cross-relaxation rates (σ) between methyl and labile protons to be determined and permits identification of methyl sites in close proximity to labile groups in the protein structure.</p>","PeriodicalId":613,"journal":{"name":"Journal of Biomolecular NMR","volume":" ","pages":""},"PeriodicalIF":1.9000,"publicationDate":"2025-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Biomolecular NMR","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1007/s10858-025-00469-8","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
We show that water saturation leads to deleterious losses in sensitivity of methyl signals in selectively methyl-[13CH3]-labeled protein samples of high molecular weight proteins dissolved in H2O. These losses arise from efficient cross-relaxation between methyl protons and proximal labile protons in the protein structure. A phenomenological model for analysis of methyl intensity decay profiles that involves exchange saturation transfer of magnetization from localized proton spins of water to various labile groups in the protein structure that, in turn, efficiently cross-relax with protons of methyl groups, is described. Analysis of methyl intensity decay profiles with this model allows cross-relaxation rates (σ) between methyl and labile protons to be determined and permits identification of methyl sites in close proximity to labile groups in the protein structure.
期刊介绍：
The Journal of Biomolecular NMR provides a forum for publishing research on technical developments and innovative applications of nuclear magnetic resonance spectroscopy for the study of structure and dynamic properties of biopolymers in solution, liquid crystals, solids and mixed environments, e.g., attached to membranes. This may include:
Three-dimensional structure determination of biological macromolecules (polypeptides/proteins, DNA, RNA, oligosaccharides) by NMR.
New NMR techniques for studies of biological macromolecules.
Novel approaches to computer-aided automated analysis of multidimensional NMR spectra.
Computational methods for the structural interpretation of NMR data, including structure refinement.
Comparisons of structures determined by NMR with those obtained by other methods, e.g. by diffraction techniques with protein single crystals.
New techniques of sample preparation for NMR experiments (biosynthetic and chemical methods for isotope labeling, preparation of nutrients for biosynthetic isotope labeling, etc.). An NMR characterization of the products must be included.
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