β-Endorphin: Structure-activity relationships in the guinea pig ileum and opiate receptor binding assays

Byron A. Doneen, David Chung, Donald Yamashiro, Ping Yee Law, Horace H. Loh, Choh Hao Li

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

The opiate activities of some derivatives and enzymatic digests of camel and human β-endorphin were determined in the guinea pig ileum and rat brain opiate receptor binding assays. Derivatives of β-endorphins altered within the amino-terminal five residues showed pronounced losses in activity. Anisylation of the C-terminal glutamic acid residue of βh-endorphin produced only small reductions in activity. Chymotryptic digestion greatly weakened the opiate activities of βh-endorphin, whereas carboxypeptidase A, tryptic and leucine aminopeptidase digests showed only small losses in potency. The C-terminus of β-endorphin appears to contribute little directly to opiate activity. Amino acid analysis and assay of the leucine aminopeptidase digests suggest that the larger potency of β-endorphin relative to Met-enkephalin may be a consequence of its greater resistance to exopeptidase attack.

Original languageEnglish (US)
Pages (from-to)656-662
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume74
Issue number2
DOIs
StatePublished - Jan 24 1977

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