Fig. 2.

Secondary structure elements of ASPC. (A) Summary of sequential and medium range NOE correlations (|i°–°j| < 5), hydrogen–deuterium exchange experiments, ³J_NH-Hα (³J_αN) values, and chemical shift indices (CSI). NOE intensities are grouped into 4 classes (2.5, 3.0, 4.0, and 5.0 Å) and are represented by the thicknesses of solid lines. Thicker lines indicate stronger NOE correlations. Open circles indicate the amide protons observed in ¹H and TOCSY spectra recorded in CD₃OD (500 MHz). Solid circles indicate the positions where ³J_NH-Hα values are larger than 8 Hz. Consensus results of CSI derived from C^αH, C^α, and C^β chemical shifts of ASPC are indicated by a ternary index with values of −1, 0 and +1. The arrows at the top of the figure indicate the positions of β-sheets as determined by a combination of strong sequential d_αN, weak d_NN, non-exchanged amide protons, large 3J_NH-Hα values, and a CSI value of +1. (B) Long-range NOE correlations (|i°–°j| ≥ 5) and H-bonds of the triple-stranded antiparallel β sheet region in ASPC. NOE correlations and H-bonds are indicated by solid arrows and dashed lines, respectively.