Dugelay S, Yang D, Soloviev M V, Previs S F, Agarwal K C, Fernandez C A, Brunengraber H
Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106.
Anal Biochem. 1994 Sep;221(2):368-73. doi: 10.1006/abio.1994.1427.
Phenylacetate, derived from phenylalanine, is converted in human and primate liver to phenylacetylglutamine. The latter, which is excreted in urine, has been used to probe noninvasively the labeling pattern of liver citric acid cycle intermediates. We present nuclear magnetic resonance assays for the urinary concentration of phenylacetylglutamine and for the 13C-labeling pattern of its glutamine moiety. The concentration of phenylacetylglutamine is calculated from the natural 13C signals of all carbons of its benzene ring and C-2 of its acetyl moiety. The limit of detection is 13 mumol of unlabeled phenylacetylglutamine. The minimum amount of phenylacetylglutamine needed to determine a 1% enrichment of one of its carbons is 26 mumol. The technique was tested by analyzing phenylacetylglutamine in the urine from monkeys infused with various 13C tracers. The labeling patterns obtained agreed with theoretical calculations and patterns reported in phenylacetylglutamine and glutamine labeled from 14C and 13C tracers, respectively.
源自苯丙氨酸的苯乙酸盐在人和灵长类动物肝脏中转化为苯乙酰谷氨酰胺。后者经尿液排出，已被用于非侵入性地探究肝脏柠檬酸循环中间产物的标记模式。我们提出了用于检测尿中苯乙酰谷氨酰胺浓度及其谷氨酰胺部分的¹³C标记模式的核磁共振分析方法。苯乙酰谷氨酰胺的浓度是根据其苯环所有碳原子的天然¹³C信号及其乙酰基部分的C-2计算得出的。检测限为13 μmol未标记的苯乙酰谷氨酰胺。确定其一个碳原子1%的富集所需的苯乙酰谷氨酰胺的最小量为26 μmol。通过分析输注各种¹³C示踪剂的猴子尿液中的苯乙酰谷氨酰胺对该技术进行了测试。获得的标记模式与理论计算结果以及分别用¹⁴C和¹³C示踪剂标记的苯乙酰谷氨酰胺和谷氨酰胺中报道的模式一致。
