Enzyme immunoassay for conjugated 7alpha-hydroxy-3-oxo-4-cholenoic acid in human urine.

A microplate enzyme immunoassay (EIA) was developed for the measurement of glycine- and taurine-conjugated 7 alpha -hydroxy-3-oxo-4-cholenoic acids (CDCA-Delta (4)-3-one) in human urine. The antiserum was prepared by immunizing rabbits with N-(7 alpha -hydroxy-3-oxo-4-cholen-24-oyl)-3-amino-propionic acid - bovine serum albumin conjugate. A colorimetric EIA was established using horseradish peroxidase-labeled antigen having a shorter bridge length than that of the immunogen, and 3, 3', 5, 5'-tetramethylbenzidine/hydrogen peroxide for the measurement of the enzyme activity.