HUMAN β‐ENDORPHIN Immunoreactivity of Synthetic Analogs with Various Chain Lengths

Abstract
Immunoreactivity of synthetic human β-endorphin analogs with various chain lengths has been examined using a specific radioimmunoassay. It was found that β-endorphin-(1–21) and analogs of shortened chain exhibit no immunoreactivity, whereas β-endorphin-(1–15) possesses significant in vitro opiate activity. It appears that immunoreactivity of β-endorphin resides in the COOH-terminal segment of residues (22–31). The data also show the lack of correlation between opiate and immunological activities of β-endorphin.