FIG. 3.

Two-dimensional [¹H-¹⁵N] HSQC spectra of the LDL-A module of Tva and its mutants. The purified ¹⁵N-labeled proteins were folded in vitro in the presence (A, B, E, F, G, and H) or absence (C and D) of calcium, and two-dimensional [¹H-¹⁵N] HSQC spectra were acquired either with added calcium (A, C, E, F, G, and H) or with no added calcium (B and D) as described in Materials and Methods. For example, wt +Ca/+Ca (A) indicates that calcium was present in the folding reaction (+Ca/) and with added calcium in NMR analysis (/+Ca).