Fig. 8.

Fluorescence spectra recorded after ABS tagging of low FSAY(3-NO₂)LER concentrations in the absence (a, b) or in the presence of tryptic peptides prepared from lysate of 100 μg C2C12 cell protein (c, d). Fluorescence tagging after nitropeptide reduction was performed with 2 mM ABS and 10 μM K₃Fe(CN)₆ in 0.1 M Na₂HPO₄ at 25°C. Concentrations of the nitropeptide in the respective samples (nM) are indicated for respective spectra. The dashed line traces represent spectra obtained through subtraction of respective background fluorescence spectra (in the absence of nitropeptide)