Biology Department, McMaster University, Hamilton, Ontario, Canada L8S 4K1.
Plant Physiol. 1978 Nov;62(5):693-5. doi: 10.1104/pp.62.5.693.
l-Canavanine inhibits the appearance of nitrate reductase (NADH-nitrate oxidoreductase, EC 1.6.6.1) in both root tips and mature root sections of corn (Zea mays L.). Ten-fold more canavanine was required to cause a 50% reduction in the level of nitrate reductase activity (NRA) in root tips than in mature root sections. For example with one particular batch of seeds 500 mum canavanine was effective in root tips whereas only 50 mum was required in mature root sections. In root tips arginine (1 mm) completely reversed the effect of 1 mm canavanine. In mature root sections higher concentrations of arginine (approximately 5 mm) were required for a complete reversal of the canavanine effect. Additions of canavanine to roots after a period of 3 hours with 5 mm KNO(3) resulted in a loss of NRA. NO(3) (-) protected nitrate reductase from this inactivation in both root tip and mature root sections.
L-瓜氨酸抑制硝酸盐还原酶（NADH-硝酸盐氧化还原酶，EC 1.6.6.1）在玉米（Zea mays L.）根尖和成熟根段中的出现。需要十倍以上的瓜氨酸才能使根尖中硝酸盐还原酶活性（NRA）降低 50%。例如，用一批特定的种子，500µM 的瓜氨酸在根尖中有效，而在成熟的根段中仅需 50µM。在根尖中，精氨酸（1mM）完全逆转了 1mM 瓜氨酸的作用。在成熟的根段中，需要更高浓度的精氨酸（约 5mM）才能完全逆转瓜氨酸的作用。将瓜氨酸添加到用 5mM KNO3 处理 3 小时后的根部，导致 NRA 丧失。NO3-（-）在根尖和成熟根段中都能保护硝酸盐还原酶免受这种失活。
