Young N D, Galston A W
Department of Biology, Yale University, New Haven, Connecticut 06511.
Plant Physiol. 1983 Apr;71(4):767-71. doi: 10.1104/pp.71.4.767.
Incubation of peeled oat Avena sativa L. var Victory leaf segments on media of pH 5.0 or below leads to a rapid and massive increase in the titer of putrescine while incubation at pH values above 5.0 causes little or no change. The low pH effect is independent of the buffer system employed. Putrescine levels rise within 3 hours and reach their peak 8 to 9 hours after acidification. At this time, putrescine titer is eight times greater at pH 3.5 than at 6.0. None of the other polyamines shows a response to changes in external pH. The increase in putrescine is blocked by the addition of cycloheximide or dl-alpha-difluoromethylarginine, a specific inhibitor of the putrescine biosynthetic enzyme, arginine decarboxylase. In one experiment, arginine decarboxylase activity was 110% greater at pH 4.0 than at 6.0 after a 4-hour incubation, although the average increase over many experiments was 47%. The activity of the other possible putrescine biosynthetic enzyme, ornithine decarboxylase, falls throughout the incubation period and is virtually equal at pH 4.0 and 6.0.
将去皮燕麦（燕麦 Avena sativa L. 变种Victory）叶片切段在pH 5.0或更低的培养基上培养，会导致腐胺滴度迅速大幅增加，而在pH值高于5.0的条件下培养则几乎没有变化。低pH效应与所使用的缓冲系统无关。腐胺水平在3小时内上升，并在酸化后8至9小时达到峰值。此时，pH 3.5时的腐胺滴度比pH 6.0时高八倍。其他多胺均未表现出对外部pH变化的响应。添加环己酰亚胺或腐胺生物合成酶精氨酸脱羧酶的特异性抑制剂dl-α-二氟甲基精氨酸可阻断腐胺的增加。在一项实验中，经过4小时培养后，pH 4.0时的精氨酸脱羧酶活性比pH 6.0时高110%，尽管在许多实验中的平均增幅为47%。另一种可能的腐胺生物合成酶鸟氨酸脱羧酶的活性在整个培养期间都下降，并且在pH 4.0和6.0时几乎相等。
