Fig. 8. Statistics-based chemical shift analysis of the 2D 2Q correlation spectra of NT(9-13). The spectrum from Fig. 2a is superimposed with rectangles that represent the expected chemical shift range for the individual resonances. The boxes are centered at the average chemical shifts, and their size is determined by two times the standard deviation. These values were taken from the most recent entries in "Restricted set of amino acid chemical shifts" found in BioMagResBank (www.bmrb.wisc.edu). Coupled spins appear at the same frequency in ω₁, further restricting the assignment. The coloring of the rectangles denotes the individual residues (as in the upper left corner of the spectrum) and the digits relate to: 1, C_α ; 2, C_β; 3, C_γ; 4, C_δ.