Figure 6.

¹⁵N–¹³C δp₀ PAIN-CP polarization transfer at ω_H0/2π = 750 MHz and ω_r/2π = 20 kHz for three different ¹³C offset frequencies, 40 ppm (a) and (b); 177 ppm (c) and (d); 110 ppm for (e) and (f). The left column correspond to favorable low power PAIN-CP settings whereas the right column to higher power PAIN-CP settings. The spin system is extracted from the Crh x-ray structure (PDB ID: 1mu4) (Ref. ³⁰) and is composed of L63N, four carbons (L63C_α, L63C_β, L63C_γ, T62C), and the four protons mainly involved in the spin dynamics (L63H, L63H_α, L63H_β2, L63Hγ). The ¹³C chemical shifts are taken from the protein assignment (Ref. ³¹). The L63N and the protons are irradiated on resonance. The simulation includes typical CSA tensor parameter for nitrogen (99 ppm, 0.19), carbonyls (−76 ppm, 0.9) and proton (5 ppm, 0.7).