Penicillinase as a marker in enzyme-linked immunosorbent assays for steroid hormones

Using penicillinase (E.C. 3.5.2.6) as marker and microtitre ELISA plates for immunoadsorption, sensitive and specific assays for two steroid hormones viz. testosterone in plasma and estrone-3-glucuronide in urine were developed. The entire assay can be performed in 4 h and requires simple laboratory equipment such as an incubator and a colorimeter. The enzyme labelled steroids have a shelf life of more than 3 years.