ASSESSMENT OF THE FREE FRACTION OF 25-HYDROXYVITAMIN-D IN SERUM AND ITS REGULATION BY ALBUMIN AND THE VITAMIN-D-BINDING PROTEIN
ASSESSMENT OF THE FREE FRACTION OF 25-HYDROXYVITAMIN-D IN SERUM AND ITS REGULATION BY ALBUMIN AND THE VITAMIN-D-BINDING PROTEIN
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DOI：
10.1210/jcem-63-4-954
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发表时间：
1986-10-01
影响因子：
5.8
通讯作者：
HADDAD, JG
中科院分区：
文献类型：
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作者：
BIKLE, DD;GEE, E;HADDAD, JG
我们测量了人血清中25-羟基维生素D（25 OHD）的游离部分，并确定25 OHD与亲和常数为7 × 10 - 6的组分结合。108 M-1和浓度为4.5 ×10-6 M.该浓度等于同一血清样品中维生素D结合蛋白（DBP）的浓度。我们用肌动蛋白亲和柱从血清中除去DBP，发现剩余血清组分对25 OHD的亲和性与人血清白蛋白的亲和性相当（6 × 104）。105 M-1）。然后，我们测量了正常和糖尿病患者的25 OHD，DBP和白蛋白的游离分数。我们计算了88 .+-. 3%（. ±. SD）和83 .+-.正常人和糖尿病患者血清中25 OHD的8%与DBP结合。我们比较了先前报道的数据，游离分数和游离浓度的1，25-二羟维生素D在这些受试者与目前的数据的游离分数和游离浓度的25 OHD。这些受试者中两种代谢物的总浓度和游离分数相互相关，并与DBP和白蛋白浓度相关，但这些代谢物的游离浓度则不相关。我们的结论是，25 OHD，像1，25-二羟维生素D，主要结合DBP和白蛋白在血液中运输。DBP和白蛋白浓度的变化影响血清中25 OHD的总量和游离分数，但25 OHD的实际游离浓度与这些变化无关。
We measured the free fraction of 25-hydroxyvitamin D (25OHD) in human serum and determined that 25OHD bound to a component with an affinity constant of 7 .times. 108 M-1 and a concentration of 4.5 .times. 10-6 M. This concentration was equal to that of the vitamin D-binding protein (DBP) in the same serum sample. We removed DBP from the serum using actin affinity columns and found that the affinity for 25OHD of the remaining serum components was equivalent to that of human serum albumin (6 .times. 105 M-1). We then measured the free fractions of 25OHD, DBP, and albumin in normal and cirrhotic subjects. We calculated that 88 .+-. 3% (.+-.SD) and 83 .+-. 8% of the 25OHD were bound to DBP in the serum of normal and cirrhotic subjects, respectively. We compared previously reported data for the free fraction and the free concentration of 1,25-dihydroxyvitamin D in these subjects with the current data for the free fraction and free concentration of 25OHD. The total concentrations and free fractions of both metabolites correlated to each other and to the DBP and albumin concentrations in these subjects, but the free concentrations of these metabolites did not. We conclude that 25OHD, like 1,25-dihydroxyvitamin D, is transported in blood bound primarily to DBP and albumin. Changes in the concentrations of DBP and albumin affected the total and free fractions of 25OHD in serum, but the actual free concentration of 25OHD was independent of such changes.