Joy K W
Plant Physiol. 1969 Jun;44(6):849-53. doi: 10.1104/pp.44.6.849.
In L. minor grown in sterile culture, the primary enzymes of nitrate assimilation, nitrate reductase (NR), nitrite reductase (NiR) and glutamate dehydrogenase (GDH) change in response to nitrogen source. NR and NiR levels are low when grown on amino acids (hydrolyzed casein) or ammonia; both enzymes are rapidly induced on addition of nitrate, while addition of nitrite induces NiR only. Ammonia represses the nitrate induced synthesis of both NR and NiR.NADH dependent GDH activity is low when grown on amino acids and high when grown on nitrate or ammonia, but the activities of NADPH dependent GDH and Alanine dehydro-genase (AIDH) are much less affected by nitrogen source. NADH-GDH and AIDH are induced by ammonia, and it is suggested that these enzymes are involved in primary nitrogen assimilation.
在无菌培养条件下生长的浮萍中，硝酸盐同化的主要酶，即硝酸还原酶（NR）、亚硝酸还原酶（NiR）和谷氨酸脱氢酶（GDH）会根据氮源的变化而改变。当浮萍在氨基酸（水解酪蛋白）或氨上生长时，NR和NiR的水平较低；添加硝酸盐时，这两种酶都会迅速被诱导，而添加亚硝酸盐时仅诱导NiR。氨会抑制硝酸盐诱导的NR和NiR的合成。当浮萍在氨基酸上生长时，依赖NADH的GDH活性较低，而在硝酸盐或氨上生长时活性较高，但依赖NADPH的GDH和丙氨酸脱氢酶（AIDH）的活性受氮源的影响要小得多。NADH-GDH和AIDH由氨诱导，有人认为这些酶参与初级氮同化过程。
