Figure 3.

Structures and MS² spectra of product N-linolenoyl-L-glutamic acid. N-Linolenoyl-L-[α−¹⁵N] glutamine was converted to¹⁵N-labeled N-linolenoyl-L-[α−¹⁵N] glutamic acid (A) and N-linolenoyl-L-[γ−¹⁵N] glutamine yielded unlabeled N-linolenoyl-L-glutamic acid (B). ¹⁵N-labeling at the α-position of the glutamine moiety was passed to corresponding glutamic acid conjugate, whereas ¹⁵N-labeling at the γ-position (side chain of glutamine) was cleaved off during its conversion.