Buy Orexin B Research Peptide

What is Orexin B?

Orexin B is the second orexin brain peptide, with 28 amino acids. Both orexins govern wakefulness and appetite, but Orexin B prefers the OX2 receptor, making it a more precise tool for studying that part of the system in animal research.

• A brain peptide studied for its role in sleep-wake and alertness signaling
• More selective for the OX2 receptor, useful for separating receptor-specific effects
• Studied in animal research on sleep-wake regulation and feeding
• Used to map how the two orexin receptors contribute to sleep and alertness

For research use only. Not approved for human therapeutic use.

Orexin B (CAS 205640-91-1), also known as Hypocretin-2, is a synthetic 28-amino acid neuropeptide with a molecular weight of 2937.42 g/mol. Unlike Orexin A, Orexin B is a linear peptide with no intramolecular disulfide bridges and no pyroglutamyl modification. While Orexin A and Orexin B share 46% sequence homology within their C-terminal regions, their structural divergence leads to distinct receptor selectivity profiles. Produced via solid-phase peptide synthesis, Hypocretin-2 acts as an endogenous agonist with high selectivity for the OX2R receptor in preclinical neuroscience research.

Orexin B has been investigated as a ligand of the orexinergic system, and its differential receptor selectivity has been characterised for dissecting OX1R- versus OX2R-mediated signalling. In vitro receptor studies have characterised Orexin B downstream signalling at OX2R relative to OX1R in transfected cell line preparations, documenting the differential receptor selectivity profile of Orexin B compared with Orexin A and characterising OX2R-preferential calcium mobilisation as primary pharmacological readouts distinguishing Orexin B from its dual-receptor counterpart in pharmacological assays [1]. In vivo rodent studies have used Orexin B as a comparator tool to examine the relative contributions of OX1R and OX2R to sleep-wake regulation, arousal maintenance, and feeding behaviour, showing wake-inducing potency between Orexin A and Orexin B following direct administration in rats, characterising the OX2R-selective profile of Orexin B as a basis for dissecting receptor subtype-specific contributions to arousal state regulation and sleep-wake circuitry [2], making Orexin B a reference compound in orexin receptor pharmacology research as the OX2R-selective tool peptide for dissecting receptor subtype-specific contributions to sleep-wake regulation and arousal state transitions.

Orexin B is produced to research-grade standards and independently verified by third-party HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

References

1Sakurai T, Amemiya A, Ishii M, Matsuzaki I, Chemelli RM, Tanaka H, et al. Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell. 1998 Feb 20;92(4):573–85. .PubMed PMID: 94918972España RA, Baldo BA, Kelley AE, Berridge CW. Wake-promoting and sleep-suppressing actions of hypocretin (orexin): basal forebrain sites of action. Neuroscience. 2001;106(4):699–715. .PubMed PMID: 11682157

Scientific Review

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed for scientific accuracy, 14 June 2026

View credentials →

Orexin B (CAS 205640-91-1), also known as Hypocretin-2, is a synthetic 28-amino acid neuropeptide with a molecular weight of 2937.42 g/mol. Unlike Orexin A, Orexin B is a linear peptide with no intramolecular disulfide bridges and no pyroglutamyl modification. While Orexin A and Orexin B share 46% sequence homology within their C-terminal regions, their structural divergence leads to distinct receptor selectivity profiles. Produced via solid-phase peptide synthesis, Hypocretin-2 acts as an endogenous agonist with high selectivity for the OX2R receptor in preclinical neuroscience research.

Orexin B has been investigated as a ligand of the orexinergic system, and its differential receptor selectivity has been characterised for dissecting OX1R- versus OX2R-mediated signalling. In vitro receptor studies have characterised Orexin B downstream signalling at OX2R relative to OX1R in transfected cell line preparations, documenting the differential receptor selectivity profile of Orexin B compared with Orexin A and characterising OX2R-preferential calcium mobilisation as primary pharmacological readouts distinguishing Orexin B from its dual-receptor counterpart in pharmacological assays [1]. In vivo rodent studies have used Orexin B as a comparator tool to examine the relative contributions of OX1R and OX2R to sleep-wake regulation, arousal maintenance, and feeding behaviour, showing wake-inducing potency between Orexin A and Orexin B following direct administration in rats, characterising the OX2R-selective profile of Orexin B as a basis for dissecting receptor subtype-specific contributions to arousal state regulation and sleep-wake circuitry [2], making Orexin B a reference compound in orexin receptor pharmacology research as the OX2R-selective tool peptide for dissecting receptor subtype-specific contributions to sleep-wake regulation and arousal state transitions.

Orexin B is produced to research-grade standards and independently verified by third-party HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

References

1Sakurai T, Amemiya A, Ishii M, Matsuzaki I, Chemelli RM, Tanaka H, et al. Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell. 1998 Feb 20;92(4):573–85. .PubMed PMID: 94918972España RA, Baldo BA, Kelley AE, Berridge CW. Wake-promoting and sleep-suppressing actions of hypocretin (orexin): basal forebrain sites of action. Neuroscience. 2001;106(4):699–715. .PubMed PMID: 11682157

Scientific Review

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed for scientific accuracy, 14 June 2026

View credentials →CAS Number205120-58-9Molecular Weight~2,937.59 g/molPurity≥98%Physical FormLyophilised PowderManufacturingManufactured in an ISO9001 Certified LaboratoryTestingHPLC + MS-UPLCSKURSC-OREXINB-0245

Lyophilised powder: store at -20 °C or below, away from light and moisture. Once reconstituted in an appropriate laboratory diluent (e.g. sterile water, PBS, or assay buffer), store at 2–8 °C and use within the validated period for your protocol. Do not refreeze.

Orexin B (CAS 205640-91-1), also known as Hypocretin-2, is a synthetic 28-amino acid neuropeptide with a molecular weight of 2937.42 g/mol. Unlike Orexin A, Orexin B is a linear peptide with no intramolecular disulfide bridges and no pyroglutamyl modification. While Orexin A and Orexin B share 46% sequence homology within their C-terminal regions, their structural divergence leads to distinct receptor selectivity profiles. Produced via solid-phase peptide synthesis, Hypocretin-2 acts as an endogenous agonist with high selectivity for the OX2R receptor in preclinical neuroscience research.

Orexin B has been investigated as a ligand of the orexinergic system, and its differential receptor selectivity has been characterised for dissecting OX1R- versus OX2R-mediated signalling. In vitro receptor studies have characterised Orexin B downstream signalling at OX2R relative to OX1R in transfected cell line preparations, documenting the differential receptor selectivity profile of Orexin B compared with Orexin A and characterising OX2R-preferential calcium mobilisation as primary pharmacological readouts distinguishing Orexin B from its dual-receptor counterpart in pharmacological assays [1]. In vivo rodent studies have used Orexin B as a comparator tool to examine the relative contributions of OX1R and OX2R to sleep-wake regulation, arousal maintenance, and feeding behaviour, showing wake-inducing potency between Orexin A and Orexin B following direct administration in rats, characterising the OX2R-selective profile of Orexin B as a basis for dissecting receptor subtype-specific contributions to arousal state regulation and sleep-wake circuitry [2], making Orexin B a reference compound in orexin receptor pharmacology research as the OX2R-selective tool peptide for dissecting receptor subtype-specific contributions to sleep-wake regulation and arousal state transitions.

Orexin B is produced to research-grade standards and independently verified by third-party HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

References

1Sakurai T, Amemiya A, Ishii M, Matsuzaki I, Chemelli RM, Tanaka H, et al. Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell. 1998 Feb 20;92(4):573–85. .PubMed PMID: 94918972España RA, Baldo BA, Kelley AE, Berridge CW. Wake-promoting and sleep-suppressing actions of hypocretin (orexin): basal forebrain sites of action. Neuroscience. 2001;106(4):699–715. .PubMed PMID: 11682157

Scientific Review

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed for scientific accuracy, 14 June 2026

View credentials →CAS Number205120-58-9Molecular Weight~2,937.59 g/molPurity≥98%Physical FormLyophilised PowderManufacturingManufactured in an ISO9001 Certified LaboratoryTestingHPLC + MS-UPLCSKURSC-OREXINB-0245

Lyophilised powder: store at -20 °C or below, away from light and moisture. Once reconstituted in an appropriate laboratory diluent (e.g. sterile water, PBS, or assay buffer), store at 2–8 °C and use within the validated period for your protocol. Do not refreeze.