Pons A, García F J, Palou A, Alemany M
J Biochem Biophys Methods. 1981 Sep;5(3):153-6. doi: 10.1016/0165-022x(81)90014-2.
A method for quantitative estimation of total radioactivity present in the free amino acid fraction of tissue samples has been described. Samples deproteinized with cold acetone were extracted, in acidic medium, with ethyl ether (peroxide free); after centrifugation, the aqueous phase was used for amino acid derivatization at 40 degrees C for 15 h with 1-fluoro-2,4-dinitrobenzene in bicarbonate-buffered medium. Aliquots of the derivatized samples were acidified and extracted twice again with ethyl ether. The combined organic phases were placed in glass scintillation vials, dried, and used for the determination of its radioactivity, corresponding to the radioactivity present in the free amino acid fraction of the sample. Deproteinized samples of rat blood plasma, as well as hen egg white and yolk were tested after addition of known quantities of 14C-labelled amino acids or glucose, for validation of the method. No glucose radioactivity was found in any of the extracted samples. All radioactivity added to the samples in the form of 14C-labelled alanine, glutamic acid, leucine and phenylalanine was quantitatively recovered in the derivatized fraction; only a fraction of arginine radioactivity was recovered.
已描述了一种用于定量估算组织样品游离氨基酸部分中总放射性的方法。用冷丙酮脱蛋白的样品在酸性介质中用（无过氧化物的）乙醚萃取；离心后，水相在40℃下于碳酸氢盐缓冲介质中用1-氟-2,4-二硝基苯进行氨基酸衍生化反应15小时。将衍生化样品的等分试样酸化，再用乙醚萃取两次。合并的有机相置于玻璃闪烁瓶中，干燥后用于测定其放射性，该放射性对应于样品游离氨基酸部分中的放射性。在添加已知量的14C标记氨基酸或葡萄糖后，对大鼠血浆、以及鸡蛋清和蛋黄的脱蛋白样品进行了测试，以验证该方法。在任何萃取样品中均未发现葡萄糖放射性。以14C标记的丙氨酸、谷氨酸、亮氨酸和苯丙氨酸形式添加到样品中的所有放射性均在衍生化部分中定量回收；仅回收了一部分精氨酸放射性。
