玉米根细胞质膜硝酸还原酶和铁氰化物还原酶活性的关系

The Relation Between Activities of Nitrate Reductase and of Ferric-yandie Reductase of Plasma Membrane in corn roots

以玉米离体根和根细胞质膜(PM)为材料,研究了加铁培养和铁胁迫条件下铁氰化物还原酶(FCR)和硝酸还原酶(NR)活性,以及两种活性间的关系,实验结果显示铁胁迫条件下FCR活性随培养天数变化较加铁培养下有较快增加,一定时间后又下降,在加入K_3Fe(CN)_6后,铁胁迫的离体根NR活性的下降明显快于加铁培养的离体根。根细胞PM在加入K_3Fe(CN)_6后,NR活性与对照比降低了5倍,甚至为零;当从介质中除去Fe^(3+)后,NR活性成倍恢复。上述结果表明在铁胁迫条件下铁氰化物的还原与硝酸根的还原间存在着强烈的电子竞争。

The activities of nitrate reductase (NR)and ferricyanide reductase(FCR)as well as relations have been studied by using root segements and plasma membrane (PM)from Maize roots under iron-deficient and iron-sufficient conditions. The results suggest that the activity of FCR in iron-deficient plant has greatly increas during the days of growth. when ferricyanide is added,marked reduction of the NR activity of root segements has been observed under iron-deficient condition which is much higher than that of iron-sufficient one. The results from PM experiment show that the activity of NR is 5-fold less than that of control when ferricyanide is added. When ferricyanide is eliminated by transforming of Fe3+to Fe2+ ,the activity of NR is recovered totally. These results indicate that ferricyanide reduction competes strongly with nitrate reduction for the electrons from donors under iron-deficient condition.