Practical procedure for enzyme immunoassay of progesterone in bovine serum

An enzyme immunoassay of progesterone was established by using beta-galactosidase from E. coli as a label. The enzyme was conjugated with 11 alpha-hydroxyprogesterone-hemisuccinate using water-soluble carbodiimide. Rabbit antiserum to 11 alpha-hydroxyprogesterone-hemisuccinate-bovine serum albumin was previously obtained and anti-rabbit gamma globulin goat serum was used as second antibody. The enzyme activity was measured by utilizing hydrolysis of O-nitrophenyl-beta-D-galactopyranoside. The least detectable concentration of progesterone was 12 pg per tube. The measurable range of progesterone in 0.1 ml of bovine serum was between 0.25 ng/ml and 10 ng/ml. This method satisfied the general criteria regarding specifity, precision and recovery rate. Correlation between the progesterone levels determined by enzyme immunoassay and radioimmunoassay was quite high (r = 0.99, P less than or equal to 0.01). The present enzyme immunoassay can be applied for practical and routine analysis of serum progesterone.