小麦籽粒氨基酸碳氮稳定同位素的测定与分析

doi:10.3864/j.issn.0578-1752.2009.02.008

中国农业科学 ›› 2009, Vol. 42 ›› Issue (2): 446-453 .doi: 10.3864/j.issn.0578-1752.2009.02.008

小麦籽粒氨基酸碳氮稳定同位素的测定与分析

中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室

收稿日期:2008-01-28 修回日期:2008-06-19 出版日期:2009-02-10 发布日期:2009-02-10
通讯作者: 梅旭荣

Measurement and Analysis of Stable Carbon and Nitrogen Isotope of Amino Acids in Wheat Grain

中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室

Received:2008-01-28 Revised:2008-06-19 Online:2009-02-10 Published:2009-02-10
Contact: MEI Xu-rong

摘要/Abstract

摘要：

【目的】利用气相色谱-燃烧-同位素比值质谱仪（gas chromatography-combustion-isotope ratio mass spectrometry，GC-C-IRMS）测定小麦籽粒氨基酸碳氮稳定同位素组成。【方法】以小麦临汾50744为材料，水解得到其籽粒蛋白质氨基酸，将氨基酸标准样品以及小麦籽粒氨基酸衍生化为N-新戊酰基，O-异丙醇（N-pivaloyl-isopropyl，NPP）氨基酸酯，利用GC-C-IRMS测定其碳氮稳定同位素组成。【结果】氨基酸标准样品的碳氮同位素组成分析表明，NPP氨基酸酯的平均重现性δ13C为0.47‰，δ15N为0.28‰，并没有产生大的同位素分馏，因此δ13C和δ15N都能得到满意的测定结果。运用GC-C-IRMS测定了小麦临汾50744籽粒蛋白质氨基酸的稳定碳氮同位素的自然丰度，其中δ13C的变化范围在-28.7‰到-34.7‰，δ15N的变化范围为-6.2‰到9.5‰。采用系统聚类分析进行分类，根据δ13C可以将氨基酸分为两类;根据δ15N可以将氨基酸分为三类。【结论】运用GC-C-IRMS结合NPP氨基酸酯衍生物可以测定小麦籽粒氨基酸的稳定碳氮同位素，这对于揭示氨基酸代谢途径的差异以及逆境胁迫下氨基酸的合成差异具有重要的意义。

关键词: GC-C-IRMS, NPP氨基酸酯, δ13C, δ15N

Abstract:

【Objective】 To measure the stable carbon and nitrogen isotope composition of amino acids in wheat grain by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). 【Method】 The N-pivaloyl-isopropyl (NPP) derivatives of the protein amino acids, which hydrolyzed with 6M HCl in wheat grain Linfen 50744, and standard amino acids were measured by GC-C-IRMS.【Result】 Analysis of stable carbon and nitrogen isotope composition of N-pivaloyl-isopropyl (NPP) amino acid standard esters shows the mean reproducibility of δ13C is 0.47‰ and δ15N is 0.28‰. Good results can be got as less isotope fractionation is observed in this study. The δ13C values of NPP derivatives were from -28.7‰ to -34.7‰, and the δ15N values of NPP derivatives were -6.2‰ to 9.5‰. Amino acids can be divided into two categories according to δ13C, and three categories according to δ15N by hierarchical cluster analysis. 【Conclusion】 It is feasible to determine the composition of stable carbon and nitrogen isotope of amino acids in wheat with NPP amino acid esters by GC-C-IRMS, which will make great significance to reveal the difference of metabolism and synthesis of amino acids under adverse environment.

Key words: GC-C-IRMS, NPP amino acid esters, δ13C, δ15N