Total folate binding capacity of normal human plasma, and variations in uremia, cirrhosis, and pregnancy.
Total folate binding capacity of normal human plasma, and variations in uremia, cirrhosis, and pregnancy.
复制标题
正常人血浆的总叶酸结合能力，以及尿毒症、肝硬化和妊娠的变化。
作者：
N. Colman;V. Herbert
目前的研究表明，所有人血清都含有一类高亲和力的叶酸结合体(Ka=2.8X10(10升/摩尔)，在凝胶过滤中呈单峰迁移。以前的研究未能在除少数受试者之外的所有受试者中发现这一特征，这可归因于其可变的、通常是完全的饱和。直接测量总叶酸结合量(TFBC)是通过在酸性pH下解离内源叶酸-结合络合物，用涂覆的木炭去除游离叶酸，以及放射性叶酸标记来实现的。这一过程似乎没有显著地变性粘合剂，它释放并重新结合类似数量的~3H-PGA。20例正常人TFBC范围为100~325pg/ml(平均+/-SE=174+/-16)，且总饱和度至少为33%。在三种与不饱和叶酸结合能力升高相关的临床情况下，当同时测量TFBC时，出现了三种不同的模式。尿毒症受试者平均TFBC显著升高，饱和度正常。在肝硬变受试者中，平均TFBC接近正常，但饱和度显著降低。在怀孕期间，可以看到两组人：一组TFBC升高，另一组TFBC正常，其中一些人的饱和度降低。干酪乳杆菌血清叶酸水平约为TFBC的30倍；两者之间没有相关性。
The current study presents evidence that all human serum contains a class of high-affinity folate binders (KA=2.8 X10(10 liters/mole), which migrate as a single peak on gel filtration. Failure of previous studies to detect this characteristic in all but a minority of subjects is attributable to its variable, often total, saturation. Direct measurement of the total folate binding capacity (TFBC) has been made possible by dissociation of endogenous folate-binder complexes at acid pH, removal of free folate by coated charcoal, and radiofolate tagging. This procedure does not appear to significantly denature the binders, which release and rebind similar quantities of 3H-PGA. In 20 normal subjects, TFBC ranged from 100 to 325 pg/ml (mean+/-SE = 174+/-16), and was always at least 33% saturated. In three clinical conditions, all associated with elevated unsaturated folate binding capacity, three different patterns emerged when TFBC was also measured. Uremic subjects had significantly elevated mean TFBC with normal saturation. In cirrhotic subjects, mean TFBC approximated normal, but saturation was significantly decreased. In pregnancy, two groups were seen: one with increased TFBC and the other with a normal TFBC, some of whom had decreased saturation. Lactobacillus casei serum folate level was about 30 times greater than the TFBC; there was no correlation between the two measurements.