Manabe S, Sassa S, Kappas A
J Exp Med. 1985 Sep 1;162(3):1060-74. doi: 10.1084/jem.162.3.1060.
Succinylacetone (SA) (4,6-dioxoheptanoic acid) is an abnormal metabolite produced in patients with hereditary tyrosinemia as a consequence of an inherited deficiency of fumaryl acetoacetate hydrolase activity. Patients with this disease are associated with a number of abnormalities, including aminoaciduria, proteinuria, liver failure, commonly hepatoma, and decreased GSH concentration in the liver. In the course of our studies of tyrosinemia, we found that the urine of patients with this disorder contains material(s) that absorbs light at 315 nm. We investigated the nature of the 315 nm material in detail. SA was found to react with amino acids and protein nonenzymatically, to form stable adducts at physiological temperature and pH. All SA adducts with amino acids and/or proteins exhibited an absorption peak at 315 nm. Although all amino acids reacted with SA, the most reactive amino acid was lysine (Lys), followed, in order, by glycine, methionine, phenylalanine, serine, alanine, and glutamine. SA-adducts were unstable at pH below 6, while they were made considerably more stable after reduction with NaBH4, suggesting that SA forms an adduct via Schiff base formation. High-performance liquid chromatography (HPLC) analysis of urines from patients with tyrosinemia revealed the existence of SA-glycine, SA-methionine, SA-tyrosine, and SA-phenylalanine. After digestion of urines with proteinase K, three more HPLC peaks appeared, which all corresponded to SA-Lys adducts. TLC analysis of SA-Lys showed that SA-Lys could form as many as seven different adducts. No SA-adduct peaks were observed in HPLC in urines from normal subjects, patients with other forms of aminoaciduria, or patients with the nephrotic syndrome. In addition to amino acids and proteins, SA reacted with reduced glutathione (GSH) and formed a stable adduct. These findings suggest that SA adduct formation with amino acids, GSH, and proteins is a significant process occurring in tyrosinemia, and may account for certain of the pathologic findings in this hereditary disorder.
琥珀酰丙酮（SA）（4,6 - 二氧代庚酸）是遗传性酪氨酸血症患者体内产生的一种异常代谢产物，这是由于遗传性的延胡索酰乙酰乙酸水解酶活性缺乏所致。患有这种疾病的患者会出现多种异常情况，包括氨基酸尿、蛋白尿、肝功能衰竭（通常会发展为肝癌）以及肝脏中谷胱甘肽（GSH）浓度降低。在我们对酪氨酸血症的研究过程中，我们发现患有这种疾病的患者尿液中含有在315nm处有吸光物质。我们详细研究了315nm物质的性质。发现SA在生理温度和pH条件下能与氨基酸和蛋白质发生非酶反应，形成稳定的加合物。所有SA与氨基酸和/或蛋白质的加合物在315nm处都有一个吸收峰。虽然所有氨基酸都能与SA反应，但反应活性最高的氨基酸是赖氨酸（Lys），其次依次是甘氨酸、蛋氨酸、苯丙氨酸、丝氨酸、丙氨酸和谷氨酰胺。SA - 加合物在pH低于6时不稳定，而在用硼氢化钠还原后稳定性显著提高，这表明SA通过席夫碱的形成形成加合物。对酪氨酸血症患者尿液进行高效液相色谱（HPLC）分析发现存在SA - 甘氨酸、SA - 蛋氨酸、SA - 酪氨酸和SA - 苯丙氨酸。用蛋白酶K消化尿液后，又出现了三个HPLC峰，它们都对应于SA - Lys加合物。SA - Lys的薄层层析（TLC）分析表明SA - Lys可以形成多达七种不同的加合物。在正常受试者、其他形式氨基酸尿患者或肾病综合征患者的尿液HPLC中未观察到SA - 加合物峰。除了氨基酸和蛋白质外，SA还与还原型谷胱甘肽（GSH）反应并形成稳定的加合物。这些发现表明SA与氨基酸、GSH和蛋白质形成加合物是酪氨酸血症中发生的一个重要过程，可能解释了这种遗传性疾病中的某些病理表现。
