What is PE-22-28?
PE-22-28 is a short synthetic peptide classified within the family of spadin-derived fragments. Its primary structure is the heptapeptide sequence Gly-Val-Ser-Trp-Gly-Leu-Arg (single-letter: GVSWGLR), which corresponds to the C-terminal 22-28 segment of spadin, a natural peptide derived from the propeptide portion of sortilin (a precursor protein processed during sortilin maturation). The molecule is linear and unmodified, presenting a free N-terminal alpha-amino group and a free C-terminal carboxyl group, with no cyclization, disulfide bridges, or synthetic capping.
Structurally, PE-22-28 carries the molecular formula C35H55N11O9 and an average molecular weight of 773.89, and is catalogued under CAS number 1234388-01-0. The seven-residue backbone combines a hydrophobic core (valine, tryptophan, leucine) with polar and charged side chains (the serine hydroxyl and the guanidinium group of the C-terminal arginine), producing an amphipathic character that informs its handling and solubility behavior in the laboratory. The indole ring of the single tryptophan residue provides an intrinsic chromophore useful for spectroscopic characterization.
In the scientific literature, PE-22-28 is studied as a spadin analog in in-vitro and preclinical neuroscience research, where the parent spadin peptide is investigated in connection with the TREK-1 (TWIK-related K+) two-pore-domain potassium channel. American Peptides supplies PE-22-28 strictly as a research reference standard for these in-vitro and laboratory model applications. It is not a drug, dietary supplement, or cosmetic, and no therapeutic or physiological outcome is claimed or implied.
Reconstitution & handling
PE-22-28 is provided as a lyophilized powder and is reconstituted by the researcher prior to use. Because the peptide combines polar serine and a positively charged C-terminal arginine with a hydrophobic core, it is generally taken up first in sterile water or a dilute aqueous buffer; mildly acidic aqueous conditions, such as a dilute acetic acid solution, can assist initial solubilization. If full dissolution is not achieved in aqueous media, a small fraction of a compatible organic co-solvent such as a low percentage of DMSO may be used to prepare a concentrated stock, which is then diluted into the working buffer. Solvent selection should reflect the downstream assay and the tryptophan residue, which is sensitive to prolonged light exposure and strong oxidants.
For best recovery, allow the sealed vial to equilibrate to room temperature before opening to minimize condensation on the hygroscopic solid, add solvent gently down the vial wall rather than directly onto the powder, and swirl rather than vortex vigorously to limit foaming and shear. Reconstituted material should be prepared in the smallest practical volume, aliquoted to avoid repeated freeze-thaw cycles, and kept on ice during use. All handling described here concerns physicochemical dissolution only and is not administration guidance.
Storage & stability
In lyophilized form, PE-22-28 is stable for extended periods when stored sealed, desiccated, and protected from light at -20 degrees C, with brief excursions to refrigerated or ambient temperature tolerated during shipping and weighing. Once reconstituted, the peptide is markedly less stable in aqueous solution and should be stored refrigerated at 2-8 degrees C for short-term use or frozen at -20 degrees C or below in single-use aliquots for longer storage; repeated freeze-thaw cycles and prolonged exposure to warm, oxygenated, or high-pH conditions should be avoided to limit hydrolysis and oxidation of the tryptophan residue.
How it's tested
Identity and purity of PE-22-28 are established analytically and documented on a lot-specific Certificate of Analysis (COA). Chromatographic purity is determined by reversed-phase high-performance liquid chromatography (RP-HPLC), with each release lot meeting a specification of not less than 99% purity by HPLC. Molecular identity is confirmed by mass spectrometry (typically ESI-MS or MALDI-TOF), where the observed mass is verified against the theoretical molecular weight of 773.89 for formula C35H55N11O9. Supporting characterization may include UV absorbance from the tryptophan chromophore and sequence confirmation, and the COA is available for each lot so researchers can verify identity, purity, and net peptide content before experimental use.