Asparagine formation in soybean nodules.

(15)NH(4) (+) and [(15)N](amide)-glutamine externally supplied to detached nodules from soybean plants (cv. Tamanishiki) were incorporated within nodule tissues by vacuum infiltration and metabolized to various nitrogen compounds during 60 minutes of incubation time. In the case of (15)NH(4) (+) - feeding, the (15)N abundance ratio was highest in the amide nitrogen of glutamine, followed by glutamate and the amide nitrogen of asparagine. In (15)N content (micrograms excess (15)N), the amide nitrogen of asparagine was most highly enriched after 60 minutes. (15)NH(4) (+) was also appreciably assimilated into alanine.When [(15)N](amide)-glutamine was fed to detached nodules, (15)N was almost entirely in the amide nitrogen of asparagine. The result indicates the presence of active glutamine-linked asparagine synthesizing systems in soybean root nodules.