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IUPAC name
(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[(2S)-6-amino-2-[[(2S)-2-[[(2S)-4-amino-2-[[(2S)-3-methyl-2-[[(2S)-pyrrolidine-2-carbonyl]amino]butanoyl]amino]-4-oxo-butanoyl]amino]-3-phenyl-propanoyl]amino]hexanoyl]amino]-3-phenyl-propanoyl]amino]-4-methyl-pentanoyl]amino]-3-hydroxy-propanoyl]amino]-3-(1H-imidazol-5-yl)propanoic acid
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Identifiers | |
3D model (JSmol)
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ChEMBL | |
ChemSpider | |
PubChem CID
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CompTox Dashboard (EPA)
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Properties | |
C53H77N13O12 | |
Molar mass | 1088.25838 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hemopressin (Hp) is an alpha hemoglobin fragment with the sequence PVNFKFLSH, originally identified in extracts of rat brain using an enzyme capture technique.[1] It binds cannabinoid receptors, acting as an inverse agonist at CB1 receptors.[2] Longer forms of hemopressin containing 2-3 additional amino acids on the N-terminus have been identified in extracts of mouse brain. These longer hemopressin peptides, named RVD-Hpα and VD-Hpα, bind to CB1 receptors and were originally reported to be agonists.[3] In addition to the Hp peptides from alpha hemoglobin, a related peptide from beta hemoglobin has been found in mouse brain extracts; this peptide, named VD-Hpβ, is also an agonist at CB1 cannabinoid receptors.[3] Hemopressin is not an endogenous peptide but rather an extraction artefact.[4] The only endogenous peptide found endogenously at physiological conditions is RVD-hemopressin (pepcan-12), which has more recently been shown to be a negative allosteric modulator of CB1 receptors and positive allosteric modulator of CB2 receptors.[4][5] RVD-hemopressin (pepcan-12) is generated from a pro-peptide called pepcan-23 and these peptides are exclusively found in noradrenergic neurons in the brain and in the adrenal medulla.[6]
The original Hp peptide reduces sensitivity to painful stimuli in an experimental model of hyperalgesia.[7] Hp also reduces food intake in mice.[8] However, it remains to be shown if Hp is an endogenous brain peptide. The original purification used boiling acid to extract the peptide from rat brain, and hot acid can specifically cleave D-P bonds. The N-terminally-extended forms RVD-Hpα and VD-Hpα may represent the true endogenous forms.[9]