FIGURE 4.

Identification of a specific dithiol-disulfide switch in CRMP2 by MALDI-TOF mass spectrometry. Mass spectra details of reduced (A.1/B.1) or oxidized (A.2/B.2) NEM-labeled CRMP2. A.1/A.2 peptide I, GLYDGPVCEVSVTPK+NEM; peptide II, GLYDGPVCEVSVTPK + NEM/H₂O at Cys-504 (A.1, I and II, theoretical masses, 1688.89/1706.81; observed, 1688.56/1706.57); B.1/B.2 peptide III, 2× GLYDGPVCEVSVTPK in form of disulfide-linked peptides (B.2, III, theoretical mass, 3124.52; observed, 3124.28) not present in the reduced protein (B.1).