高等植物最重要的氮源是土壤中的硝酸盐,但硝酸盐必须经过代谢还原才能被利用.这种还原作用通常认为是按下面式子进行的:上述四个还原步骤的第一步,即硝酸盐还原成亚硝酸盐的反应,是由细胞质中的硝酸还原酶(NR)催化的.NR是由底物诱导生成的,它以FAD作为辅酶,同时还含有钼和铁的黄素蛋 The most important nitrogen source for higher plants is nitrate in the soil, but nitrate must be metabolically reduced before it can be utilized.This reduction is usually thought of as follows: The first of these four reduction steps, namely The reaction of nitrate reduction to nitrite is catalyzed by nitrate reductase (NR) in the cytoplasm, which is induced by the substrate and which uses FAD as a coenzyme, together with flavin eggs of molybdenum and iron