Karg E, Orvos H, Papp A, Beck N, Turi S, Nemeth I
Department of Pediatrics, University of Szeged, Albert Szent-Györgyi Medical School, H-6724 Szeged, Koranyi fasor 14-15, Hungary.
Free Radic Res. 2001 Nov;35(5):555-61. doi: 10.1080/10715760100301561.
In the neonatal period, there is a high iron load, while both the level and molar oxidase activity of ceruloplasmin are low. On the other hand, the neonatal xanthine oxidase (XO) activity is higher than later in life and XO has a significant iron-oxidizing capacity. We therefore studied the physiological contribution of XO to the ferroxidase activity of the plasma in 20 full-term newborn infants. Ferroxidase activity was measured spectrophotometrically, with Fe++ as substrate. The uric acid formed by XO was assayed by means of HPLC, with electrochemical detection. The total ferroxidase activity in the plasma was about one-fourth of the adult level and rapidly increased doubling within 3 days after birth. About 90% of the plasma ferroxidase activity was due to ceruloplasmin, the remainder being accounted for by ferroxidase II. The XO activity underwent a 30% (statistically non-significant) elevation at 24 h, though ferroxidase activity attributable to XO was not detected at any time. Accordingly, XO does not seem to add substantially to the total iron-oxidizing capacity of the plasma in the neonatal period. The high molar ferroxidase activity is probably of importance at the endothelial cell surface.
在新生儿期，铁负荷较高，而铜蓝蛋白的水平和摩尔氧化酶活性均较低。另一方面，新生儿黄嘌呤氧化酶（XO）活性高于生命后期，且XO具有显著的铁氧化能力。因此，我们研究了20名足月新生儿中XO对血浆铁氧化酶活性的生理贡献。以Fe++为底物，采用分光光度法测定铁氧化酶活性。通过高效液相色谱法（HPLC）和电化学检测法测定XO产生的尿酸。血浆中的总铁氧化酶活性约为成人水平的四分之一，并在出生后3天内迅速翻倍。约90%的血浆铁氧化酶活性归因于铜蓝蛋白，其余部分由铁氧化酶II所致。尽管在任何时间均未检测到归因于XO的铁氧化酶活性，但XO活性在24小时时升高了30%（无统计学意义）。因此，在新生儿期，XO似乎对血浆的总铁氧化能力没有实质性贡献。高摩尔铁氧化酶活性在内皮细胞表面可能具有重要意义。
