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. Author manuscript; available in PMC: 2008 Feb 1.
Published in final edited form as: J Magn Reson. 2006 Nov 27;184(2):350–356. doi: 10.1016/j.jmr.2006.10.012

Figure 2.

Figure 2

(a-d) 13C CPMAS spectra of protein micro crystals for (a, b) lysozyme and (c, d) ubiquitin prepared in D2O obtained (a, c) with and (b, d) without 10 mM Cu-EDTA at 13C NMR frequency of 100.6 MHz. The recycle delays were (a) 0.18 s, (b) 1.50 s, (c) 0.18 s, and (d) 2.50 s. The spectra were acquired at a spinning speed of 40 kHz with π-pulse-train decoupling. In the decoupling scheme, a π-pulse with the width of 2.5 μs was rotor-synchronously applied at the end of every rotor cycle (25 μs) with the XY-8 phase cycle.[51] Signals were accumulated during acquisition periods of 20 ms with (a) 36,000, (b) 4,800, (c) 72,000, and (d) 5,680 scans in a common total experimental time of (a, b) 2 hours or (c, d) 4 hours. During the CP period of 1.0 ms, the 13C RF field was swept from 53 kHz to 71 kHz, while the 1H RF field was kept at 102 kHz. All the spectra were processed with Gaussian line broadening of 15 Hz.