ISOELECTRIC FOCUSING OF HUMAN α‐FETOPROTEIN: AN AID IN PURIFICATION AND CHARACTERIZATION OF MICROHETEROGENEITY
ISOELECTRIC FOCUSING OF HUMAN α‐FETOPROTEIN: AN AID IN PURIFICATION AND CHARACTERIZATION OF MICROHETEROGENEITY
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人 α-胎蛋白的等电聚焦：有助于微异质性的纯化和表征
DOI：
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发表时间：
1973
影响因子：
5.2
通讯作者：
K. Isselbacher
中科院分区：
文献类型：
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作者：
E. Alpert;J. Drysdale;K. Isselbacher
甲胎蛋白（AFP），一种胎儿特异性血清蛋白，1是由胚胎肝细胞在妊娠的前三个月合成并分泌到血清中。2 AFP是由恶性肝细胞再合成的，随后再次出现在原发性肝癌4和胚胎癌患者的血清中。6人血清中AFP的检测是第一个临床上有用的人类恶性肿瘤血清学标志物的基础。6为了发展定量放射免疫测定法，最近已经进行了几次纯化这种癌胚蛋白的尝试。在我们对人胎蛋白进行测定和表征的过程中，我们通过等电聚焦8发现了微异质性的证据，我们试图使用这种强大的新工具来表征。尽管人胎蛋白在1956年被证明，令人惊讶的是，直到最近，人们对它的物理或化学特性知之甚少。AFP以快速α-1-球蛋白或后白蛋白的形式迁移（在pH 8.6时），11表明负电荷相当高。通过葡聚糖凝胶过滤12和SDS聚丙烯酰胺电泳8，确定其分子量约为72，000，并且没有可检测到的碳水化合物的报道。AFP被认为是均一的电泳，11通过凝胶过滤，12和通过超离心。18通过免疫沉淀和随后的酸洗脱分离的AFP的研究最近证实了这些明显均一的蛋白质的特征，但提示微量的碳水化合物。
Alpha-fetoprotein (AFP), a fetal specific serum protein,l is synthesized by embryonic liver cells in the first trimester of gestation and secreted into serum.2 AFP is resynthesized by malignant liver cells and subsequently reappears in the serum of patients with primary liver carcinoma4 and embryonal carcinoma.6 The detection of AFP in human sera is the basis of the first clinically useful serologic marker of a human malignancy.6 Several attempts have recently been made to purify this carcinoembryonic protein in order to develop a quantitative radioimmunoassay.e-~ In the course of our irolation and characterization of human fetoprotein, we encountered evidence of microheterogeneity by means of isoelectric focusing8 that we have attempted to characterize using this powerful new tool.10 Although human fetoprotein was demonstrated in 1956,11 surprisingly little was known about its physical or chemical characteristics until relatively recently. AFP migrates electrophoretically (at pH 8.6) as a rapid alpha-1-globulin or postalbumin,11 indicating a fairly high negative charge. Its molecular weight has been determined to be approximately 72,000 by means of Sephadex gel filtration12 and SDS polyacrylamide electrophoresis,8 and there has been no detectable carbohydrate reported. AFP has been considered homogeneous eIectrophoretically,11 by gel filtration,12 and by ultracentrifugation.18 Studies of AFP isolated by immune precipitation and subsequent acid elution have recently confirmed these characteristics of an apparently homogeneous protein, but suggested trace amounts of carbohydrate.Q$13