A novel two-site enzyme immunoassay for the sensitive detection of beta-endorphin in specific human brain stem regions.

On the line of experiences previoulsy made in the development of a two-site immunoradiometric assay (TS-IRMA), we generated, in the present study, a novel, sequential, noncompetitive two-site immunoenzymometric assay (TS-IEMA) for the determination of the non-acetylated form of human β-endorphin (βh-EP). At variance with other assays reported in the literature, but in analogy to the TS-IRMA, the TS-IEMA does not require previous separation of βh-EP