Compound monograph
TRH (thyrotropin-releasing hormone)
Protirelin is a tripeptide comprising L-pyroglutamyl, L-histidyl and L-prolinamide units in that order.
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Identity & nomenclature
Protirelin is a tripeptide comprising L-pyroglutamyl, L-histidyl and L-prolinamide units in that order.
Protirelin names the parent without counterion or hydrate. A D-His-qualified name is excluded. The additional CAS lead remains unqualified. An unresolved historical erratum linkage and receptor-bound model differences do not establish an alternative free-parent structure.
Canonical name: Protirelin.
Declared aliases and development codes: Thyrotropin-releasing hormone, TRH, Thyrotropin-releasing factor, TRF.
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Molecular properties
| Molecular formula | C16H22N6O4 |
|---|---|
| Molecular mass | 362.39 Da |
| CAS Registry Number | 24305-27-9 |
| PubChem CID | 638678 |
| UNII | 5Y5F15120W |
| Three-letter sequence | pGlu–His–Pro |
| Terminal groups | N-terminal pyroglutamate; C-terminal amide |
pGlu denotes L-pyroglutamyl at position 1, rather than open-chain Glu or Gln. His2 and Pro3 are L. The pyroglutamyl lactam is within the first unit and is not an inter-residue ring. Terminal prolinamide is recorded separately; no one-letter sequence is supplied.
03
Structural characteristics
pGlu denotes L-pyroglutamyl at position 1, rather than open-chain Glu or Gln. His2 and Pro3 are L. The pyroglutamyl lactam is within the first unit and is not an inter-residue ring. Terminal prolinamide is recorded separately; no one-letter sequence is supplied.
- Pyroglutamate at position 1
Terminal features: N-terminal pyroglutamate, C-terminal amide.
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Molecular targets & mechanisms
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Analytical considerations
The molecular formula describes the parent; the average mass is calculated using CIAAW 2024 abridged atomic weights. Japanese Pharmacopoeia XVIII prints 362.38, a non-defining difference of +0.010 Da (+27.595 ppm). PubChem also displays 362.38, without an established explanation of its atomic-weight table. An early incompletely characterized isolation preparation had a tentative mass around 1000; its equivalence to the exact parent is unresolved.
What the studies reported
No verified findings are published for this record under Content Policy v1.
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Verified bibliography
Cited studies by type
The 2 papers this record cites, counted by the kind of work each reports. A count is the size of this record's selection, not of the research that exists, and says nothing about results, safety, effectiveness or approval.
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Reference 1
The identity of chemical and hormonal properties of the thyrotropin releasing hormone and pyroglutamyl-histidyl-proline amide.Boler J, Enzmann F, Folkers K, Bowers CY, Schally AV
Biochemical and biophysical research communications · 1969-11-06 · Journal Article
currentReference 2
Characterization of ovine hypothalamic hypophysiotropic TSH-releasing factor.Burgus R, Dunn TF, Desiderio D, Ward DN, Vale W, Guillemin R
Nature · 1970-04-25 · Journal Article
current
Study models of these references
What kind of experiment each cited paper reports, taken from its abstract unless marked. Not a summary of results.
| Reference | Study models |
|---|---|
| Boler J et al. 1969 | Chemical, structural or analytical study; no biological model reported |
| Burgus R et al. 1970 | Chemical, structural or analytical study; no biological model reportedCorrection published: Nature. 1970 May 2;226(5244):479 |
Record history
Published 2026-10-21.
No changes to this record's content have been recorded since publication.
Each entry names the parts of this record that changed on that date. Changes to links between records and to catalogue links are not listed. This history covers the tracked record fields; study findings are not listed here.
Cite this record: Purely Peptides Research Library. TRH (thyrotropin-releasing hormone). Published 2026-10-21. https://purelypeptides.org/research/compounds/trh/
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Methodology & citation verification
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