FIGURE 3.

NOESY spectra showing the aliphatic region of native and recombinant κ-BUTX-Tt2b spectra obtained with 0. 1 mm native (48 h of acquisition in red) and with 2.3 mm recombinant (in black). Differences are attributed to concentration and the glycine and serine in the N termini. The inset shows the correlations between Cys⁷ and Cys²⁰ forming the cystine pair C2-C4 for the recombinant protein (Cys⁷ HB₂–Cys²⁰ HB₂, Cys⁷ HB₂–Cys²⁰ HB₃, Cys⁷ HB₃–Cys²⁰ HB₂, and Cys⁷ HB₃–Cys²⁰ HB₃ with distances found of 4.9, 4.0, 3.4, and 4.0 Å).