Bauer A, Urquhart A A, Joy K W
Department of Biology, Carleton University, Ottawa, Canada K1S 5B6.
Plant Physiol. 1977 May;59(5):915-9. doi: 10.1104/pp.59.5.915.
In the young leaves of pea (Pisum sativum L.) plants, there was a diurnal variation in the levels of amino acids. In the light, total amino nitrogen increased for the first few hours, then stabilized; in the dark, there was a transient decrease followed by a gradual recovery. Asparagine, homoserine, alanine, and glutamine accounted for much of these changes. The incorporation of (15)N into various components of the young leaves was followed after supply of (15)N-nitrate. (15)N appeared most rapidly in ammonia, due to reduction in the leaf, and this process took place predominantly in the light. A large proportion of the primary assimilation took place through the amide group of glutamine, which became labeled and turned over rapidly; labeling of glutamic acid and alanine was also rapid. Asparagine (amide group) soon became labeled and showed considerable turnover. Slower incorporation and turnover were found for aspartic acid, gamma-aminobutyric acid, and homoserine. Synthesis and turnover of all of the amino acids continued at a low rate in the dark. gamma-Aminobutyric acid was the only compound found to label more rapidly in the dark than in the light.
在豌豆（Pisum sativum L.）植株的幼叶中，氨基酸水平存在昼夜变化。在光照下，总氨基氮在最初几个小时增加，然后稳定下来；在黑暗中，会有短暂下降，随后逐渐恢复。天冬酰胺、高丝氨酸、丙氨酸和谷氨酰胺占了这些变化的大部分。在供应¹⁵N-硝酸盐后，追踪¹⁵N在幼叶各个成分中的掺入情况。¹⁵N在氨中出现得最快，这是由于叶片中的还原作用，并且这个过程主要发生在光照下。大部分初级同化作用通过谷氨酰胺的酰胺基团进行，该基团被标记且周转迅速；谷氨酸和丙氨酸的标记也很快。天冬酰胺（酰胺基团）很快被标记并显示出相当大的周转。天冬氨酸、γ-氨基丁酸和高丝氨酸的掺入和周转较慢。在黑暗中，所有氨基酸的合成和周转都以较低速率继续。γ-氨基丁酸是唯一被发现其在黑暗中比在光照下标记更快的化合物。
