Abstract
INEPT-based experiments are widely used for 1H→15N transfers, but often fail when involving labile protons due to solvent exchanges. J-based cross polarization (CP) strategies offer a more efficient alternative to perform such transfers, particularly when leveraging the Hwater (Formula presented.) HN exchange process to boost the 1H→15N transfer process. This leveraging, however, demands the simultaneous spin-locking of both Hwater and HN protons by a strong 1H RF field, while fulfilling the γHB1,H=γNB1,N Hartmann-Hahn matching condition. Given the low value of γN/γH, however, these demands are often incompatible—particularly when experiments are executed by the power-limited cryogenic probes used in contemporary high field NMR. The present manuscript discusses CP alternatives that can alleviate this limitation, and evaluates their performance on urea, amino acids, and intrinsically disordered proteins. These alternatives include new CP variants based on frequency-swept and phase-modulated pulses, designed to simultaneously fulfill the aforementioned conflicting conditions. Their performances vis-à-vis current options are theoretically analyzed with Liouville-space simulations, and experimentally tested with double and triple resonance transfer experiments.
Original language | English |
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Article number | e202304900 |
Journal | Angewandte Chemie - International Edition |
Volume | 62 |
Issue number | 35 |
Early online date | 5 Jul 2023 |
DOIs | |
Publication status | Published Online - 5 Jul 2023 |
Funding
Funding Information: We are grateful to Profs. I. Kuprov, P. Selenko and to Dr. M. Jaroszewicz for valuable discussions. JK and JTG were supported by the Israel Academy of Sciences and Humanities & Council for Higher Education Excellence Fellowship Program for International Postdoctoral Researchers. LF holds the Bertha and Isadore Gudelsky Professorial Chair and Heads the Clore Institute for High‐Field Magnetic Resonance Imaging and Spectroscopy, whose support is acknowledged. This work was supported by Israel Science Foundation Grants 1874/22 and 2790/22, the Perlman Family Foundation, and the EU Horizon 2020 program (FET‐OPEN Grant 828946, PATHOS). Publisher Copyright: © 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.
All Science Journal Classification (ASJC) codes
- Catalysis
- General Chemistry