Enzyme amplification--a general method applied to provide an immunoassisted assay for placental alkaline phosphatase

A method is described in which enzyme amplification is used for the quantitative determination of placental alkaline phosphatase. In this particular application, placental alkaline phosphatase is captured on a solid surface by means of a monoclonal antibody. The enzyme is then determined by dephosphorylation of NADP to NAD which activates a strictly NAD-dependent redox cycle leading to the formation of a coloured product.