Perfusion immunoassay for acetylcholinesterase: analyte detection based on intrinsic activity

A quantitative, two-column, HPLC-based assay requiring only 30 min to complete is reported. Amniotic fluid proteins are first fractionated on a size-exclusion column; the fraction containing the M(r) 280,000 neural acetylcholinesterase (AChE) is then diverted to a second column, an ImmunoDetection cartridge derivatized with an anti-AChE antibody. The immobilized antibody traps the enzyme, then substrate is flowed through the cartridge and the product is detected. For a positive result, the enzyme must have a molecular mass corresponding to the neural-AChE, be recognized by the antibody and be active in converting the substrate into product. The assay is sensitive in the clinically relevant range. The method provides rapid quantitative analysis using an automated instrument projected to be suitable for screening large numbers of samples.