FIGURE 6.

ESI-MS detection of NAAG and NAAG₂ in sciatic nerves. A, ESI-MS spectrum of peptide extracts of sciatic nerves and liver from wild-type mice. Mass peaks of m/z = 302.2 and 432.1, corresponding to NAAG and NAAG₂, respectively, were detectable in sciatic nerves but not in the liver. B, the fragmentation pattern of the m/z = 432.1 mass peak obtained from sciatic nerve peptide extracts was in line with the NAAG₂ structure (see fragmentation scheme in Fig. 4C), and comparable with the fragmentation pattern of synthetic NAAG₂ (see supplemental Fig. S2).