Figure 4.

Concentrations of unlabeled, ¹⁵N-amino-labeled, and ¹⁵N-amide-labeled soluble amino acids in pea root nodules after an 8-h incubation period in ¹⁵N₂ in the perfusion system and acquisition of the in vivo ¹⁵N NMR spectra shown in Figure 2.