Characterization of beta-endorphin immunoreactive peptides in rat pituitary and brain by coupled gel and reversed-phase high-performance liquid chromatography.

A procedure which combines gel high-performance liquid chromatography (HPLC) and reversed-phase HPLC in two systems with radioimmunoassay was developed for the analysis of beta-endorphin (beta END)-related peptides in rat pituitary and brain. The gel HPLC system allows rapid screening for relative amounts of precursors and products involved in beta END biosynthesis. Reversed-phase HPLC reveals minor post-translational modifications, such as acetylation, which greatly alter the biological activity of beta END. The application of this coupled procedure clearly demonstrates tissue-specific differences in the processing of beta END in pituitary and brain regions and indicates that the system may be generally applicable to the analysis of neuropeptide heterogeneity.