Figure 3.

2D MAS ssNMR on LUV-bound U-¹³C,¹⁵N cyt-c. (a) ¹³C-¹³C ssNMR spectrum on 0.75 mg reduced ¹³C,¹⁵N-cyt-c bound to DOPC/TOCL (4/1) LUVs at a P/L = 1:40. Off-diagonal crosspeaks are due to ¹³C-labeled protein, with selected residue types indicated. The dashed box indicates the region enlarged in (b). The spectrum was obtained using 15 ms DARR mixing, at 236 K, 8.33 kHz MAS, and 600 MHz (¹H frequency). (b and c) Spectral regions before and after conversion of membrane-bound reduced cyt-c to the oxidized state. Minor chemical shift and intensity changes affect Ile and other methyl-bearing residues. Arrows indicate the Met-80 ¹³C^ε chemical shift for reduced cyt-c in solution (46). To see this figure in color, go online.