Cegelski Lynette, Schaefer Jacob
Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA.
J Biol Chem. 2005 Nov 25;280(47):39238-45. doi: 10.1074/jbc.M507053200. Epub 2005 Sep 13.
Solid-state (13)C NMR measurements of intact soybean leaves labeled by (13)CO(2) (at subambient concentrations) show that excess glycine from the photorespiratory C(2) cycle (i.e. glycine not part of the production of glycerate in support of photosynthesis) is either fully decarboxylated or inserted as (13)C-labeled glycyl residues in proteins. This (13)C incorporation in leaf protein, which is uniformly (15)N labeled by (15)NH(4)(15)NO(3), occurs as soon as 2 min after the start of (13)CO(2) labeling. In those leaves with lower levels of available nitrogen (as measured by leaf nitrate and glutamine-glutamate concentrations), the excess glycine is used primarily as glycyl residues in protein.
对以（13）CO₂（在低于环境浓度下）标记的完整大豆叶片进行的固态（13）C核磁共振测量表明，光呼吸C₂循环中过量的甘氨酸（即不参与支持光合作用的甘油酸生产的甘氨酸）要么完全脱羧，要么以（13）C标记的甘氨酰残基形式插入蛋白质中。这种在叶片蛋白质中的（13）C掺入，该蛋白质已被（15）NH₄（15）NO₃均匀（15）N标记，在（13）CO₂标记开始后2分钟就会发生。在那些可用氮水平较低的叶片中（通过叶片硝酸盐和谷氨酰胺 - 谷氨酸浓度测量），过量的甘氨酸主要用作蛋白质中的甘氨酰残基。
