Baur B, Suormala T, Bernoulli C, Baumgartner E R
Metabolic Unit, University Children's Hospital, Basel, Switzerland.
Int J Vitam Nutr Res. 1998;68(5):300-8.
A microbiological, an avidin-binding and a streptavidin-binding method for biotin determination were compared. All three methods detected biotin equally well but they exhibit different specificities for derivatives of biotin. The microbiological assay has the highest specificity and is the method of choice for biotin determination in biotinidase-deficient patients. The specificity of streptavidin-binding has not been investigated so far. Application of the three methods to urine samples of patients with and without biotin therapy indicated that only 50% of biotin equivalents measured with the avidin method correspond to authentic biotin as previously shown. The other 50% comprise mainly bisnorbiotin and biotin-d-sulfoxide. HPLC-separation of urine samples prior to assay confirmed this finding and revealed a bisnorbiotin oxidation product and an unknown compound as further biotin metabolites. The latter was measurable by all three methods and not detectable in plasma ultrafiltrate. This was the only metabolite which was able to restore deficient 3-methylcrotonyl-CoA carboxylase activity in biotin-deficient fibroblasts. The combination of the three methods together with HPLC-separation proved to be a valuable analytical tool for the identification of the main biotin metabolites in biological fluids.
对用于生物素测定的微生物法、抗生物素蛋白结合法和链霉抗生物素蛋白结合法进行了比较。这三种方法对生物素的检测效果相当，但它们对生物素衍生物具有不同的特异性。微生物测定法具有最高的特异性，是生物素酶缺乏患者生物素测定的首选方法。链霉抗生物素蛋白结合法的特异性迄今尚未得到研究。将这三种方法应用于接受和未接受生物素治疗的患者的尿液样本，结果表明，如先前所示，抗生物素蛋白法测得的生物素当量中只有50%与真实生物素相对应。另外50%主要包括双降生物素和生物素 -d- 亚砜。测定前对尿液样本进行高效液相色谱分离证实了这一发现，并揭示了一种双降生物素氧化产物和一种未知化合物作为进一步的生物素代谢物。后者可通过所有三种方法检测到，而在血浆超滤液中无法检测到。这是唯一能够恢复生物素缺乏的成纤维细胞中缺陷的3-甲基巴豆酰辅酶A羧化酶活性的代谢物。这三种方法与高效液相色谱分离相结合被证明是鉴定生物体液中主要生物素代谢物的有价值的分析工具。
