Some Unusual Characteristics of Nitrate Reduction in Erythrina Senegalensis Dc.

S ummary The characteristics of nitrate reduction exhibited by the tropical leguminous tree Erythrina senegalensis differ in several respects from those of other higher plants. Nitrate reduction in this species can best be characterized as being a high activity‐low affinity system. High levels of nitrate reductase can be demonstrated using in vivo (50 to 278 μmol h −1 g fresh wt −1 ) or in vitro (360 μmol h −1 g fresh wt −1 ) assay procedures. The enzyme extracted from leaf tissue can utilize both NADH and NADPH as electron donors. The enzyme has a low affinity for nitrate, K spp 194 8 to 10 mM. The NADH and NADPH activities co‐chromatograph using several chromatographic procedures, suggesting a single molecular form of nitrate reductase is present.