Johnson J L, Wuebbens M M, Mandell R, Shih V E
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
Biochem Med Metab Biol. 1988 Aug;40(1):86-93. doi: 10.1016/0885-4505(88)90108-9.
The metabolic status of a patient previously characterized as deficient in sulfite oxidase was reexamined applying new methodology which has been developed to distinguish between a defect specific to the sulfite oxidase protein and sulfite oxidase deficiency which arises as a result of molybdenum cofactor deficiency. Urothione, the metabolic degradation product of the molybdenum cofactor, was undetectable in urine samples from the patient. Analysis of molybdenum cofactor levels in fibroblasts by monitoring reconstitution of apo nitrate reductase in extracts of the Neurospora crassa mutant nit-1 revealed that cells from the patient were severely depleted. Quantitation of urinary oxypurines showed that hypoxanthine and xanthine were highly elevated while uric acid remained in the normal range. These results were interpreted to indicate a severe but incomplete deficiency of the molybdenum cofactor. The presence of very low levels of active cofactor, supporting the synthesis of low levels of active sulfite oxidase and xanthine dehydrogenase, could explain the metabolic patterns of sulfur and purine products and the relatively mild clinical symptoms in this individual.
采用新方法对一名先前被诊断为亚硫酸盐氧化酶缺乏的患者的代谢状况进行了重新检查，该新方法旨在区分亚硫酸盐氧化酶蛋白特异性缺陷和因钼辅因子缺乏导致的亚硫酸盐氧化酶缺乏。在患者的尿液样本中未检测到钼辅因子的代谢降解产物尿硫酮。通过监测粗糙脉孢菌突变体nit-1提取物中脱辅基硝酸还原酶的重组来分析成纤维细胞中的钼辅因子水平，结果显示患者细胞中的钼辅因子严重缺乏。尿中氧嘌呤的定量分析表明，次黄嘌呤和黄嘌呤水平显著升高，而尿酸仍在正常范围内。这些结果被解释为表明钼辅因子存在严重但不完全缺乏的情况。极低水平的活性辅因子的存在，支持了低水平活性亚硫酸盐氧化酶和黄嘌呤脱氢酶的合成，这可以解释该个体中硫和嘌呤产物的代谢模式以及相对较轻的临床症状。
