FIG. 4.

Impact of cysteine on protein expression in C. difficile VPI 10463. Sonicates of 14-h cultures in PY (A) or PY plus 30 mM cysteine (B) were analyzed by 2-D PAGE. Protein (15 μg) was loaded onto each gel. Circles highlight proteins consistently found to be down-regulated by cysteine in three experiments (between 3- and >100-fold difference in spot intensity), and the numbered protein spots were subjected to N-terminal sequencing (Table 1). Molecular weights in thousands (left) and pI (bottom) are indicated.