FIG. 6.
Fluorescence detection of the interaction of CheZ peptides with CheY-P. Nineteen-amino-acid peptides corresponding to the C terminus of wild-type CheZ (AGVVASQDQVDDLLDSLGF) (●) or CheZV205E (AGVVASQDQEDDLLDSLGF) (▴) were added to CheY (20 μM) in the presence of phosphoramidate (100 mM) in 50 mM NaPi (pH 7.2)–20 mM MgCl2. The fluorescence intensity of CheY-P (λex = 285 nm; λem = 340 nm) was monitored after each addition, corrected for dilution due to volume changes, and expressed as the percentage of the fluorescence of CheY-P in the absence of added peptide.