beta-Galactosidase-linked immunoassay of prostaglandin F2 alpha

A sensitive and specific enzyme immunoassay for prostaglandin F2 alpha was developed in which prostaglandin F2 alpha was labeled with beta-D-galactosidase. After competitive binding to antibody between enzyme-labeled and free prostaglandin F2 alpha, the immunoreactive product was precipitated by double antibody technique, and the enzyme activity of the precipitate was determined fluorometrically. The procedures allowed determination of 0.03-20 pmol of prostaglandin F2 alpha. The detection limit of 0.03 pmol was comparable with that of previously reported radioimmunoassays. Enzyme immunoassay and radioimmunoassay showed almost the same cross-reactivity with other prostaglandins and metabolites.