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Purification and sequence of rat oxyntomodulin
N L Collie1, J H Walsh, H C Wong
1Department of Physiology, School of Medicine, University of California, Los Angeles 90024.
Summary
Researchers identified rat oxyntomodulin, an intestinal peptide, using a novel radioimmunoassay. This finding enables precise physiological studies of this important enteroglucagon peptide.
Area of Science:
- Endocrinology
- Molecular Biology
- Peptide Chemistry
Background:
- Previous structural data for rat enteroglucagon relied on indirect methods like cDNA and immunologic assays.
- Accurate identification of in vivo enteroglucagon forms is crucial for physiological studies.
Purpose of the Study:
- To precisely identify the in vivo forms of rat enteroglucagon.
- To enable physiological testing of synthetic enteroglucagon peptides.
Main Methods:
- Synthesis of an enteroglucagon C-terminal octapeptide common to glicentin and oxyntomodulin.
- Development of a specific radioimmunoassay using antibodies against the octapeptide.
- Purification and structural characterization (amino acid composition, microsequence, mass spectrometry) of purified rat enteroglucagon.
Main Results:
- A specific radioimmunoassay was developed, distinguishing enteroglucagon from glucagon.
- Purification of a major enteroglucagon form from rat intestine.
- Structural analysis identified the purified peptide as rat oxyntomodulin (37 residues), comprising pancreatic glucagon with a specific C-terminal extension.
Conclusions:
- Rat oxyntomodulin has been unambiguously identified and structurally characterized.
- This identification allows for the synthesis of an exact duplicate for future physiological research.
- The study provides a foundation for understanding enteroglucagon function in rats.