OXA(17-33)  (Synonyms: Orexin A (17-33) (human, mouse, rat, bovine))

OXA (17-33) (Orexin A (17-33) (human, mouse, rat, bovine)) is the shortest active orexin peptide that selectively targets OX1 (EC₅₀=8.29 nM), with 23-fold selectivity for the OX1 receptor over the OX2 receptor. The activity of OXA (17-33) depends on the Tyr17, Leu20, Asn25, His26 residues and the spatial conformation of the α-helix. OXA (17-33) activates signaling pathways involving inositol-1,4,5-trisphosphate receptor (IP3R), phospholipase D (PL-D) and choline-Sigma-1R, thereby increasing the cytoplasmic Ca²⁺ level in nucleus accumbens neurons, an effect that is blocked by Sigma-1R antagonists. OXA (17-33) serves as an important biological probe for investigating the function of the OX1 receptor. OXA (17-33) can be modified via incorporation of mixed disulfide bonds of homocysteine and cysteamine, and is widely used in studies related to insomnia and narcolepsy^[1][2][3].

OXA(17-33) (0.1-100 nM) dose-dependently increases cytosolic calcium concentration in cultured nucleus accumbens neurons via activation of OX₁ receptors, with a transient response observed at the 10 nM concentration^[2].
OXA(17-33) (10 nM) increases cytosolic calcium concentration in cultured nucleus accumbens neurons in Ca²⁺-free saline via an IP₃ receptor-dependent mechanism, with no contribution from endo-lysosomal calcium stores^[2].
OXA(17-33) (10 nM) increases cytosolic calcium concentration in cultured nucleus accumbens neurons via a choline-Sigma-1R-dependent mechanism, as inhibition of PLD or antagonism of Sigma-1R reduces the magnitude of the response^[2].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

1748.98

C₇₉H₁₂₅N₂₃O₂₂

343268-91-7

Solid

White to off-white

Tyr-Glu-Leu-Leu-His-Gly-Ala-Gly-Asn-His-Ala-Ala-Gly-Ile-Leu-Thr-Leu-NH2

YELLHGAGNHAAGILTL-NH2

Room temperature in continental US; may vary elsewhere.

Sealed storage, away from moisture and light, under nitrogen

*In solvent : -80°C, 6 months; -20°C, 1 month (sealed storage, away from moisture and light, under nitrogen)

* Please refer to the solubility information to select the appropriate solvent. Once prepared, please aliquot and store the solution to prevent product inactivation from repeated freeze-thaw cycles.
Storage method and period of stock solution: -80°C, 6 months; -20°C, 1 month (sealed storage, away from moisture and light, under nitrogen). When stored at -80°C, please use it within 6 months. When stored at -20°C, please use it within 1 month.

* Note: If you choose water as the stock solution, please dilute it to the working solution, then filter and sterilize it with a 0.22 μm filter before use.

• [1]. German NA, et al. Truncated Orexin Peptides: Structure-Activity Relationship Studies. ACS Med Chem Lett. 2013;4(12):1224-1227.  [Content Brief]

  [2]. Barr J L, et al. Choline-Sigma-1R as an additional mechanism for potentiation of orexin by cocaine[J]. International Journal of Molecular Sciences, 2021, 22(10): 5160.

  [3]. Einsiedel J, et al. Development of disulfide-functionalized peptides covalently binding G protein-coupled receptors. Bioorg Med Chem. 2022;61:116720.