Figure 9.

(A) 2D RAD spectrum of AMY10 fibrils, obtained at 150.7 MHz ¹³C NMR frequency with MAS at 21.00 kHz and a 1000 ms exchange period. Arrows indicate crosspeaks between ¹³C NMR signals of Phe15 aromatic carbons and Ile26/Leu27 methyl carbons (solid lines), Asn14 C_α carbons (dashed lines), and Phe15 C_α and C_β carbons (dotted lines). (B) 1D RAD spectrum of AMY10 fibrils, obtained at 150.7 MHz ¹³C NMR frequency with MAS at 25.00 kHz and a 1000 ms exchange period after selective preparation of longitudinal spin polarization on Phe15 aromatic carbons. Assignments of aliphatic ¹³C NMR signals that arise from polarization transfer from the Phe15 aromatic carbons are shown. (C) 2D RAD spectrum of AMY08 fibrils, obtained at 150.7 MHz ¹³C NMR frequency with MAS at 18.00 kHz and a 500 ms exchange period. Arrows indicate crosspeaks between ¹³C NMR signals of Phe23 aromatic carbons and Gly24 C_α carbons (dashed lines) and Phe23 C_α and C_β carbons (dotted lines). Short dotted arrows indicate crosspeaks that arise from MAS sidebands of Phe23 carbonyl signals. Contour levels in 2D plots increase by successive factors of 1.5.