Development and validation of a sensitive radioimmunoassay for naturally occuring β-endorphin-like peptides in human plasma

✍ Scribed by Vartan E. Ghazarossian; Robert R. Dent; Keiko Otsu; Maureen Ross; Brian Cox; Avram Goldstein

• Publisher: Elsevier Science
• Year: 1980
• Tongue: English
• Weight: 785 KB
• Volume: 102
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(80)90321-8

✦ Synopsis

3-Endorphin-like peptides in blood plasma of normal human subjects were studied by means of a radioimmunoassay (RIA) and gel filtration. Plasma was extracted with silica gel, which was washed with water and 1 N HCI, and eluted with 50% acetone. Plasma extracts thus obtained and standard synthetic human /3-endorphin yielded parallel RIA curves. Total immunoreactivity in normal donors ranged from 1.2 to 10.4 fmollml (21 subjects). The immunoreactivity was completely destroyed by treatment with papain. Gel filtration indicated the presence of three components-one of unknown nature at the void volume and the others at elution positions characteristic of /3-lipotropin and /3-endorphin. Recoveries of human P-endorphin and P-lipotropin added to plasma were 53 and 58%. respectively. Addition of N-ethylmaleimide to plasma or of aprotinin to blood immediately following collection had no effect on the amount of total immunoreactivity. Furthermore, a large amount of Plipotropin added to blood immediately following collection did not increase the amount of /3-endorphin-like immunoreactivity. The above results lead us to conclude that a P-endorphin-like immunoreactive peptide occurs naturally in plasma of normal human subjects.