Ubbink J B, Bissbort S, van den Berg I, de Villiers L S, Becker P J
Department of Chemical Pathology, University of Pretoria, South Africa.
Am J Clin Nutr. 1989 Dec;50(6):1420-8. doi: 10.1093/ajcn/50.6.1420.
A new, sensitive, two-step method free from interference by hemoglobin that measures erythrocyte glutamate-pyruvate transaminase (E-GPT) activity is described. Several aspects of E-GPT activity as an index of vitamin B-6 nutritional status were investigated with this method. 1) GPT shows a structural genetic polymorphism with two common alleles resulting in three phenotypes. In a population study (n = 92) E-GPT activity differed significantly (p less than 0.001) among the three phenotypic groups. Plasma pyridoxal-5'-phosphate concentrations in the three groups did not differ significantly. Therefore, E-GPT activity can only be used to assess vitamin B-6 nutritional status if GPT phenotype is accounted for. 2) Pyridoxine supplementation (10 mg/d) significantly (p less than 0.0001) increased E-GPT activity and decreased (p less than 0.0001) the percentage stimulation by pyridoxal-5'-phosphate in vitro although the absolute amount of in vitro stimulation by pyridoxal-5'-phosphate changed only marginally. 3) Inorganic phosphate inhibits in vitro activation of E-GPT by pyridoxal-5'-phosphate.
本文描述了一种新的、灵敏的两步法，该方法可测定红细胞谷丙转氨酶（E-GPT）活性，且不受血红蛋白干扰。使用该方法研究了E-GPT活性作为维生素B-6营养状况指标的几个方面。1）GPT存在结构基因多态性，有两个常见等位基因，产生三种表型。在一项群体研究（n = 92）中，三个表型组之间的E-GPT活性差异显著（p < 0.001）。三组血浆磷酸吡哆醛浓度无显著差异。因此，只有考虑GPT表型，E-GPT活性才能用于评估维生素B-6营养状况。2）补充吡哆醇（10 mg/d）可显著（p < 0.0001）提高E-GPT活性，并降低（p < 0.0001）体外磷酸吡哆醛的刺激百分比，尽管磷酸吡哆醛体外刺激的绝对量仅略有变化。3）无机磷酸盐可抑制磷酸吡哆醛对E-GPT的体外激活。
