17α-Hydroxy-4-pregenen-3-one (17 αP) assay, using acetylcholinesterase enzyme as tracer

17a-hydroxy-4-pregnen-3-one (17aP) hormone is a precursor of other steroid hormones and radioimmunoassay has already been used to measure it, but a simple and rapid "Enzyme Linked Immunosorbant Assay" (ELISA) is described and validated here. A general procedure for prepara-tion of the acetylcholinesterase labelled steroid is described, which is applicable to any steroid. Use of acetylcholinesterase tracer increased the sensitivity of assay so that reliable measurements of each steroid could be achieved with only 10 ml of plasma. The ELISA was applied to measure 17, 20a-hydroxy-4-pregnen-3-one (17, 20aP) steroid production from 17aP by 20 a-hydroxy steroid dehydrogenase (20a-HSD) from sperm of roach (Rutilus rutilus). The results showed that cyprinid sperm contains potent and active 20a-HSD enzymes which produce 17, 20aP hormone from 17aP substrate.