Figure 1.
The ion chromatograms of (A) 15N3-CIT and (B) 15N3-ARG in cell lysate samples after cells were incubated with 100 μM of 15N4-ARG. A peak with m/z of 179.2→71.1 and a retention time of 2.83 min (panel A) was assigned as that for 15N3-CIT. A peak with m/z of 178.2→71.1 and a retention time of 3.33 minutes (panel B) was assigned as 15N3-ARG based on their theoretical m/z and retention times.