Figure 2.

¹⁵N enrichment distributions for all peptides identified in (A) #5133 ¹⁵N T_160d and (B) #3731 ¹⁵N T_326d incubations. In both cases, the precursor pool of ${\text{NH}}_4^{+}$ was 496 μM and 1 mM of ¹⁵${\text{NH}}_4^{+}$ was added at the beginning of the incubation period.