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Isolation and structure of pro-methionine-enkephalin: Potential enkephalin precursor from porcine hypothalamus

W Y Huang1, R C Chang, A J Kastin

  • 1Endocrine and Polypeptide Laboratory, Veterans Administration Medical Center, New Orleans, Louisiana 70146.

Proceedings of the National Academy of Sciences of the United States of America
|December 1, 1979
PubMed

Insights

Researchers discovered a novel hexapeptide, pro-methionine-enkephalin, in pig hypothalami. This peptide may represent a new precursor pathway for [Met]enkephalin in the brain.

Area of Science:

  • Neuroscience
  • Biochemistry
  • Endocrinology

Background:

  • The biosynthesis of endogenous opioids, such as [Met]enkephalin, is complex.
  • Existing models suggest precursors like pro-opiomelanocortin (POMC) and proenkephalin (PE).
  • The precise pathways for all opioid peptide generation remain under investigation.

Purpose of the Study:

  • To isolate and characterize novel peptides from porcine hypothalami.
  • To investigate potential new precursors of [Met]enkephalin.
  • To determine the opioid activity of the newly identified peptide.

Main Methods:

  • Acid extraction of porcine hypothalami.
  • Peptide isolation and purification.
  • Amino acid sequencing of the isolated peptide.
  • In vitro opiate activity assays.

Main Results:

  • Isolation of a hexapeptide, pro-methionine-enkephalin (H-Tyr-Gly-Gly-Phe-Met(O)-Arg-OH).
  • The peptide is not a fragment of beta-lipotropin or beta-endorphin.
  • Synthetic pro-methionine-enkephalin demonstrated low but significant in vitro opiate activity.
  • Findings imply larger, uncharacterized precursors of [Met]enkephalin.

Conclusions:

  • Pro-methionine-enkephalin represents a potential novel precursor for [Met]enkephalin.
  • This suggests an alternative biosynthetic pathway for [Met]enkephalin.
  • The existence of larger opioid peptide precursors is strongly indicated.

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