Magic angle spinning (MAS) NMR structure determination is rapidly developing. We demonstrate a method to determine 1 H-13 C distances r CH with high precision from Lee-Goldburg cross-polarization (LG-CP) with fast MAS and continuous LG decoupling on uniformly 13 C-enriched tyrosine‚HCl. The sequence is γ-encoded, and 1 H-13 C spin-pair interactions are predominantly responsible for the polarization transfer while proton spin diffusion is prevented. When the CP amplitudes are set to a sideband of the Hartmann-Hahn match condition, the LG-CP signal builds up in an oscillatory manner, reflecting coherent heteronuclear transfer. Its Fourier transform yields an effective 13 C frequency response that is very sensitive to the surrounding protons. This 13 C spectrum can be reproduced in detail with MAS Floquet simulations of the spin cluster, based on the positions of the nuclei from the neutron diffraction structure. It is symmetric around ω ) 0 and yields two well-resolved maxima. Measurement of CH distances is straightforward, since the separation ∆ω /2π between the maxima for a single 1 H-13 C pair is related to the internuclear distance according to r CH ) a(∆ω/2π) -1/3 , with a ) 25.86 ( 0.01 Å Hz 1/3 . For the 1 H directly bonded to a 13 C, the magnetization is transferred in a short time of ∼100 µs. After this initial rapid transfer period, the COOH, OH, or NH 3 that are not directly bonded to a 13 C transfer magnetization over long distances. This offers an attractive route for collecting long-range distance constraints and for the characterization of intermolecular hydrogen bonding.

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