MICROHETEROGENEITY OF HUMAN ALPHA-FETOPROTEIN

人类 α-胎蛋白的微观异质性

• 批准号: 3322034
• 负责人: BROOKS ALLEN KEEL
• 金额: $ 6.8万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-09-01 至 1992-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3322034
• 关键词: alpha fetoprotein; amniocentesis; biological polymorphism; calmodulin; carbohydrate sequence; charge transfer complex; chemical structure; congenital disorders; congenital nervous system disorder; electrofocusing; gel filtration chromatography; genetic disorder diagnosis; gestational age; human pregnant subject; human tissue; isomer; oligosaccharides; pregnancy disorder; prenatal diagnosis; protein structure; radioimmunoassay

Alphafetoprotein (AFP), a glycoprotein, consists of two sub- fractions with respect to its affinity for the lectin concanavalin A (con A). The percentage of the con A non-reactive AFP has been shown to be significantly lower in amniotic fluid from pregnancies associated with neural tube defect. Human AFP has also been shown to exist as a series or family of charge isomers, each isomer differing in isoelectric point. Charge microheterogeneity, as well as differences in con A binding, of other glycoproteins has been attributed to subtle differences in carbohydrate structure. Because AFP exhibits carbohydrate-microheterogeneity, it is reasonable to assume that the differences observed in the proportion of con A non-reactive AFP as a result of neural tube defect will reflect changes in the isoelectric pattern of AFP. Aliquots of amniotic fluid samples obtained during routine diagnostic amniocentesis in the second trimester of pregnancy will be used. Careful attention will be paid to the gestational age at which the sample is obtained. The total concentration of AFP will be determined in each sample by specific radioimmunoassay (RIA). The charge microheterogeneity of AFP will be determined by subjecting aliquots of amniotic fluid to chromatofocusing, a technique which separates proteins according to pI. The AFP in each fraction of the column will be measured by RIA. The immunoreactive peaks, corresponding to the various charge isomers, will be pooled. The carbohydrate-microheterogeneity of the charge isomers as well as native AFP in amniotic fluid will be further assessed by con A column chromatography. Differences in the charge microheterogeneity of AFP between normal and abnormal pregnancies will be compared. The results of the proposed study should increase our knowledge of the biochemical properties of human AFP and improve our ability for prenatal diagnosis of birth defects.

甲胎蛋白（AFP）是一种糖蛋白，由两个亚 与凝集素伴刀豆球蛋白 A 的亲和力相关的分数 （con A）。 非反应性 AFP 的百分比已 怀孕期间羊水明显减少 与神经管缺陷有关。 人类 AFP 也被 显示以一系列或家族的电荷异构体存在，每个 等电点不同的异构体。 电荷微观不均匀性， 以及其他糖蛋白的 con A 结合差异 归因于碳水化合物结构的细微差异。 由于 AFP 表现出碳水化合物微异质性，因此 合理地假设观察到的差异 由于神经管导致的 con A 非反应性 AFP 的比例 缺陷将反映 AFP 等电模式的变化。 常规过程中获得的羊水样本的等分试样 妊娠中期诊断性羊膜穿刺术 将被使用。 将密切关注胎龄 获得样品的时间。 AFP总浓度 将通过特定的放射免疫测定法测定每个样品 （RIA）。 AFP 的电荷微观不均匀性将被确定 通过对等份羊水进行色谱聚焦， 根据等电点 (pI) 分离蛋白质的技术。 法新社在 柱的每个部分都将通过 RIA 进行测量。 这 免疫反应峰，对应于各种电荷 异构体，将被汇集。 碳水化合物的微观异质性 羊水中的电荷异构体以及天然 AFP 将是 通过 con A 柱色谱进一步评估。 差异在于 正常和 AFP 之间的电荷微异质性 将比较异常妊娠。 结果 拟议的研究应该增加我们对生化的了解 人类 AFP 的特性并提高我们的产前能力 出生缺陷的诊断。