Glutamine: precursor or nitrogen donor for citrulline synthesis?
Glutamine: precursor or nitrogen donor for citrulline synthesis?
复制标题
DOI：
10.1152/ajpendo.00080.2010
复制
发表时间：
2010-07-01
影响因子：
5.1
通讯作者：
Lee, Brendan
中科院分区：
文献类型：
--
作者：
Marini, Juan C.;Didelija, Inka Cajo;Lee, Brendan
马立杰，李建平，李建平，等。谷氨酰胺对瓜氨酸合成的影响[J] .中国生物医学工程学报，2009,31(2):559 - 559。首次发表于2010年4月20日；doi: 10.1152 / ajpendo.00080.2010。-尽管谷氨酰胺被认为是合成瓜氨酸的主要前体，但目前的文献并没有区分谷氨酰胺碳骨架与非特异性氮（即氨）和谷氨酰胺氧化产生的碳的贡献。为了阐明谷氨酰胺和非特异性氮在瓜氨酸合成中的作用，我们给小鼠灌胃L-[2-(15)N]-和L-[5-(15)N]谷氨酰胺和（15）N-乙酸铵。谷氨酰胺的氨基几乎相等地标记瓜氨酸的三个氮基团。胺基和乙酸铵标记瓜氨酸的脲基和氨基，但不标记三角氮。D(5)-谷氨酰胺也被注入到本研究中，它可以追踪谷氨酰胺的碳骨架，但利用率很低，仅占循环瓜氨酸的0.2-0.4%。饲粮谷氨酰胺氮（两个氮组）掺入量是其碳骨架掺入瓜氨酸的25倍。为了研究谷氨酰胺、精氨酸和脯氨酸的碳骨架和非特异性碳对瓜氨酸合成的相对贡献，我们灌胃了这些氨基酸的U-(13)C(n)示踪剂。膳食精氨酸是合成瓜氨酸的主要前体，约占循环瓜氨酸的40%。脯氨酸的贡献很小（3.4%），谷氨酰胺的贡献可以忽略不计（0.4%）。然而，谷氨酰胺示踪剂导致尿素基团的富集，表明谷氨酰胺氧化产生的非特异性碳掺入用于合成瓜氨酸的氨甲酰磷酸中。综上所述，日粮谷氨酰胺虽然为瓜氨酸的合成提供了非特异性氮和碳，但对于瓜氨酸的合成来说，它是一个较差的碳骨架前体。
Marini JC, Didelija IC, Castillo L, Lee B. Glutamine: precursor or nitrogen donor for citrulline synthesis? Am J Physiol Endocrinol Metab 299: E69-E79, 2010. First published April 20, 2010; doi:10.1152/ajpendo.00080.2010.-Although glutamine is considered the main precursor for citrulline synthesis, the current literature does not differentiate between the contribution of glutamine carbon skeleton vs. nonspecific nitrogen (i.e., ammonia) and carbon derived from glutamine oxidation. To elucidate the role of glutamine and nonspecific nitrogen in the synthesis of citrulline, L-[2-(15)N]- and L-[5-(15)N] glutamine and (15)N-ammonium acetate were infused intragastrically in mice. The amino group of glutamine labeled the three nitrogen groups of citrulline almost equally. The amido group and ammonium acetate labeled the ureido and amino groups of citrulline, but not the delta-nitrogen. D(5)-glutamine also infused in this arm of the study, which traces the carbon skeleton of glutamine, was utilized poorly, accounting for only 0.2-0.4% of the circulating citrulline. Dietary glutamine nitrogen (both N groups) incorporation was 25-fold higher than the incorporation of its carbon skeleton into citrulline. To investigate the relative contributions of the carbon skeleton and nonspecific carbon of glutamine, arginine, and proline to citrulline synthesis, U-(13)C(n) tracers of these amino acids were infused intragastrically. Dietary arginine was the main precursor for citrulline synthesis, accounting for similar to 40% of the circulating citrulline. Proline contribution was minor (3.4%), and glutamine was negligible (0.4%). However, the glutamine tracer resulted in a higher enrichment in the ureido group, indicating incorporation of nonspecific carbon from glutamine oxidation into carbamylphosphate used for citrulline synthesis. In conclusion, dietary glutamine is a poor carbon skeleton precursor for the synthesis of citrulline, although it contributes both nonspecific nitrogen and carbon to citrulline synthesis.