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预期应用
ELISA法定量测定人血清、血浆或其它相关液体中PAPP-A含量。
实验原理
本试剂盒应用双抗体夹心酶标免疫分析法测定标本中PAPP-A水平。用纯化的抗体包被微孔板，制成固相抗体，往包被单抗的微孔中依次加入PAPP-A抗原、生物素化的抗人PAPP-A抗体、HRP标记的亲和素，经过彻底洗涤后用底物TMB显色。TMB在过氧化物酶的催化下转化成蓝色，并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的PAPP-A呈正相关。用酶标仪在450nm波长下测定吸光度（OD值），计算样品浓度。
Intended use
This immunoassay kit allows for the specific measurement of human PAPP-A concentrations in serum, and plasma.
Introduction
Pregnancy-associated plasma protein-A (PAPP-A, Insulin-like growth factor binding protein-4 protease, PAPP-A-proMBP complex) is a large heterottetrameric glycoprotein of approximately 500 kDa, which was first discovered in serum from pregnant women. The hetreotetramer consists of two PAPP-A subunits and two proMBP subunits. Low maternal serum levels of PAPP-A in first trimester biochemical screening is used as a marker of Down’s syndrome.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal antibody specific for PAPP-A has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any PAPP-A present is bound by the immobilized antibody. An enzyme-linked monoclonal antibody specific for PAPP-A is added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of PAPP-A bound in the initial step. The color development is stopped and the intensity of the color is measured.
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