Shelp B J, Ireland R J
Department of Horticultural Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Plant Physiol. 1985 Mar;77(3):779-83. doi: 10.1104/pp.77.3.779.
In leaf pieces from nodulated soybean (Glycine max [L] Merr cv Maple Arrow) plants, [(14)C]urea-dependent NH(3) and (14)CO(2) production in the dark showed an approximately 2:1 stoichiometry and was decreased to less than 11% of the control (12-19 micromoles NH(3) per gram fresh weight per hour) in the presence of 50 millimolar acetohydroxamate, a urease inhibitor. NH(3) and CO(2) production from the utilization of [2-(14)C] allantoin also exhibited a 2:1 stoichiometry and was reduced to a similar extent by the presence of acetohydroxamate with a concomitant accumulation of urea which entirely accounted for the loss in NH(3) production. The almost complete sensitivity of NH(3) and CO(2) production from allantoin and urea metabolism to acetohydroxamate, together with the observed stoichiometry, indicated a path of ureide assimilation (2.0 micromoles per gram leaf fresh weight per hour) via allantoate, ureidoglycolate, and glyoxylate with the production of two urea molecules yielding, in turn, four molecules of NH(3) and two molecules of CO(2).
在结瘤大豆（Glycine max [L] Merr cv Maple Arrow）植株的叶片切片中，黑暗条件下依赖于[(14)C]尿素的NH(3)和(14)CO(2)生成呈现出约2:1的化学计量比，并且在存在50毫摩尔乙酰氧肟酸（一种脲酶抑制剂）的情况下，其生成量降至对照值（每克鲜重每小时12 - 19微摩尔NH(3)）的不到11%。利用[2-(14)C]尿囊素产生的NH(3)和CO(2)也呈现出2:1的化学计量比，并且由于乙酰氧肟酸的存在而在相似程度上降低，同时伴有尿素的积累，尿素的积累完全解释了NH(3)生成量的减少。尿囊素和尿素代谢产生的NH(3)和CO(2)对乙酰氧肟酸几乎完全敏感，再加上观察到的化学计量比，表明了一条通过尿囊酸、脲基乙醇酸和乙醛酸的酰脲同化途径（每克叶片鲜重每小时2.0微摩尔），两个尿素分子的生成依次产生四个NH(3)分子和两个CO(2)分子。
