Enhanced MALDI-TOF MS Analysis of Phosphopeptides Using an Optimized DHAP/DAHC Matrix

Figure 3

The MALDI mass spectra of the tryptic digest of (a) and (c) 𝛼-casein and (b) and (d) 𝛽-casein measured in positive (upper) and negative (lower) ion modes with the DHAP/DAHC matrix. The amount of the tryptic peptides mixture ranged from 5 fmol to 250 fmol on target. The signal intensity is magnified 5-fold in the m/z range from 2400 to 3150 in section a.

(a)

(b)

(c)

(d)