Figure 4.

Oxidative cross-linking between introduced cysteines. Extent of oxidative cross-linking catalyzed by Cu(phenanthroline)₃ was determined for cysteine pairs in homologous positions in the two subunits of the Trg homodimer using the same three membrane preparations used for experiments in Fig. 3 ▶. Mean values of percent cross-linking with std. dev. are plotted by residue number displayed from cytoplasm to periplasm for the TM1 (A) and TM2 regions (B). No data are shown for positions 199, 200, and 222 because of ambiguity in the results.