Hansen S I, Holm J, Lyngbye J
Clin Chem. 1982 Jan;28(1):117-8.
A minor cow's whey protein associated with beta-lactoglobulin is used as binding protein in the competitive radioassay for serum and erythrocyte folate. Seeking to optimize the assay, we tested the performance of binder solutions of increasing purity. The folate binding protein was isolated from cow's whey by means of CM-Sepharose CL-6B cation-exchange chromatography, and further purified on a methotrexate-AH-Sepharose 4B affinity matrix. In contrast to beta-lactoglobulin, the purified protein did not bind folate unless the detergents cetyltrimethylammonium (10 mmol/L) or Triton X-100 (1 g/L) were present. Such detergent activation was not needed in the presence of serum. There seems to be a striking analogy between these phenomena and the well-known reactivation of certain purified membrane-derived enzymes by surfactants (lipids/detergents).
一种与β-乳球蛋白相关的微量牛乳清蛋白被用作血清和红细胞叶酸竞争性放射分析中的结合蛋白。为了优化该分析方法，我们测试了纯度不断提高的结合剂溶液的性能。叶酸结合蛋白通过CM-琼脂糖凝胶CL-6B阳离子交换色谱从牛乳清中分离出来，并在甲氨蝶呤-AH-琼脂糖凝胶4B亲和基质上进一步纯化。与β-乳球蛋白不同，纯化后的蛋白除非存在十六烷基三甲基铵（10 mmol/L）或 Triton X-100（1 g/L）去污剂，否则不会结合叶酸。在有血清存在的情况下则不需要这种去污剂激活。这些现象与表面活性剂（脂质/去污剂）对某些纯化的膜衍生酶的著名再激活之间似乎存在惊人的相似之处。
