Direct Assay of Enzymes in Heme Biosynthesis for the Detection of Porphyrias by Tandem Mass Spectrometry. Uroporphyrinogen Decarboxylase and Coproporphyrinogen III Oxidase
摘要:
我们报告了血红素生物合成途径中尿卟啉原脱羧酶(UROD)和共卟啉原 III 氧化酶(CPO)的新测定方法。所开发的检测方法分别用于遗传性皮肤卟啉症和遗传性共卟啉症的临床诊断。电喷雾离子化串联质谱法用于监测由 UROD 催化的五卟啉原 I 或尿卟啉原 III 的脱羧过程,并通过测定共卟啉原 I 或 III 的生成量来确定人红细胞中酶的活性。经测定,五卟啉原 I 的 Km 值为 0.17 ± 0.03 μM。此外,还开发了一种质谱测定法,用于测定人淋巴细胞线粒体中 CPO 催化的共卟啉原 III 到原卟啉原 IX 的两步脱羧氧化反应(Km = 0.066 ± 0.009 μM)。这些检测方法具有良好的重现性,通过液-液萃取酶产物进行简单的处理,并采用市售底物和内标。
Direct Assay of Enzymes in Heme Biosynthesis for the Detection of Porphyrias by Tandem Mass Spectrometry. Uroporphyrinogen Decarboxylase and Coproporphyrinogen III Oxidase
摘要:
我们报告了血红素生物合成途径中尿卟啉原脱羧酶(UROD)和共卟啉原 III 氧化酶(CPO)的新测定方法。所开发的检测方法分别用于遗传性皮肤卟啉症和遗传性共卟啉症的临床诊断。电喷雾离子化串联质谱法用于监测由 UROD 催化的五卟啉原 I 或尿卟啉原 III 的脱羧过程,并通过测定共卟啉原 I 或 III 的生成量来确定人红细胞中酶的活性。经测定,五卟啉原 I 的 Km 值为 0.17 ± 0.03 μM。此外,还开发了一种质谱测定法,用于测定人淋巴细胞线粒体中 CPO 催化的共卟啉原 III 到原卟啉原 IX 的两步脱羧氧化反应(Km = 0.066 ± 0.009 μM)。这些检测方法具有良好的重现性,通过液-液萃取酶产物进行简单的处理,并采用市售底物和内标。
Direct Assay of Enzymes in Heme Biosynthesis for the Detection of Porphyrias by Tandem Mass Spectrometry. Uroporphyrinogen Decarboxylase and Coproporphyrinogen III Oxidase
作者:Yuesong Wang、Paula Gatti、Martin Sadílek、C. Ronald Scott、František Tureček、Michael H. Gelb
DOI:10.1021/ac702130n
日期:2008.4.1
We report new assays of enzymes uroporphyrinogen decarboxylase (UROD) and coproporphyrinogen III oxidase (CPO) in the heme biosynthetic pathway. The assays were developed for use in clinical diagnostics of inherited disorders porphyria cutanea tarda and hereditary coproporphyria, respectively. Electrospray ionization tandem mass spectrometry is used to monitor the decarboxylation of pentaporphyrinogen I or uroporphyrinogen III catalyzed by UROD and to determine the enzyme activity in human erythrocytes by measuring the production of coproporphyrinogen I or III. The Km value for pentaporphyrinogen I was measured as 0.17 ± 0.03 μM. A mass spectrometric assay was also developed for the two-step decarboxylative oxidation of coproporphyrinogen III to protoporphyrinogen IX catalyzed by CPO in mitochondria from human lymphocytes (Km = 0.066 ± 0.009 μM). The assays show good reproducibility, use simple workup by liquid−liquid extraction of enzymatic products, and employ commercially available substrates and internal standards.
我们报告了血红素生物合成途径中尿卟啉原脱羧酶(UROD)和共卟啉原 III 氧化酶(CPO)的新测定方法。所开发的检测方法分别用于遗传性皮肤卟啉症和遗传性共卟啉症的临床诊断。电喷雾离子化串联质谱法用于监测由 UROD 催化的五卟啉原 I 或尿卟啉原 III 的脱羧过程,并通过测定共卟啉原 I 或 III 的生成量来确定人红细胞中酶的活性。经测定,五卟啉原 I 的 Km 值为 0.17 ± 0.03 μM。此外,还开发了一种质谱测定法,用于测定人淋巴细胞线粒体中 CPO 催化的共卟啉原 III 到原卟啉原 IX 的两步脱羧氧化反应(Km = 0.066 ± 0.009 μM)。这些检测方法具有良好的重现性,通过液-液萃取酶产物进行简单的处理,并采用市售底物和内标。