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Primary structure and morphine-like activity of human beta-endorphin
Canadian Journal of Biochemistry
|June 1, 1977
Summary
Human beta-endorphin, a peptide with morphine-like activity, shares its amino acid sequence with the carboxy-terminal of human beta-lipotropin (beta-LPH). Beta-lipotropin itself shows no significant opiate activity.
Area of Science:
- Biochemistry
- Neuroscience
- Pharmacology
Background:
- Human beta-endorphin is a peptide with known analgesic properties.
- The relationship between beta-endorphin and beta-lipotropin (beta-LPH) has been investigated.
Purpose of the Study:
- To determine the complete amino acid sequence of human beta-endorphin.
- To compare the sequence and biological activity of beta-endorphin with beta-lipotropin.
Main Methods:
- Automatic sequencing of a sulfonyl isothiocyanate derivative of beta-endorphin.
- Peptide mapping of a tryptic digest of native beta-endorphin.
- Mouse vas deferens bioassay to assess morphine-like activity.
- Opiate receptor binding assays.
Main Results:
- The amino acid sequence of human beta-endorphin was identified as identical to the carboxy-terminal portion (61-91) of human beta-lipotropin.
- Beta-endorphin demonstrated significant morphine-like activity in both bioassays and receptor binding assays.
- Beta-lipotropin showed no significant opiate activity even at high concentrations (10(-6) M).
Conclusions:
- Human beta-endorphin is the biologically active fragment of beta-lipotropin responsible for morphine-like effects.
- This finding clarifies the molecular basis of beta-endorphin's activity and its relationship to its precursor protein.