What is P-21?
P-21 is a short synthetic peptide classified as a hexapeptide, meaning its backbone is assembled from six amino acid residues. Its documented sequence is Ac-Asp-Gly-Gly-Leu-Ala-Gly-NH2, a motif described as being derived from ciliary neurotrophic factor (CNTF). As a peptidomimetic fragment, it reproduces a small structural region of a larger parent protein rather than the full-length molecule.
Structurally, the peptide carries two defined terminal modifications: an N-terminal acetyl group (Ac-) and a C-terminal primary amide (-NH2). N-terminal acetylation caps the free alpha-amino group, while C-terminal amidation neutralizes the terminal carboxylate. Both modifications are common in synthetic peptide chemistry because they reduce terminal charge and are frequently used to increase resistance to exopeptidase cleavage in vitro. The sequence is composed of small residues — aspartic acid (Asp), glycine (Gly), leucine (Leu), and alanine (Ala) — with glycine occupying three of the six positions, contributing conformational flexibility to the short chain.
Within the scientific literature, P-21 is associated with neurotrophic and neuroscience research as a CNTF-derived peptide studied in in-vitro and preclinical model systems. It is offered strictly as a reference material for laboratory investigation. This monograph describes only the chemical identity, physical handling, and analytical characterization of the compound; it makes no claim regarding biological activity, efficacy, or suitability for use in humans or animals.
Reconstitution & handling
P-21 is supplied as a lyophilized (freeze-dried) solid and should be brought to room temperature in a sealed vial before opening to minimize condensation onto the hygroscopic powder. For reconstitution, a defined volume of solvent is introduced slowly against the interior vial wall and allowed to dissolve without vigorous agitation; gentle swirling is preferred over shaking to limit foaming and mechanical stress on the peptide. Bacteriostatic or sterile water is a common baseline solvent for laboratory handling. Because this sequence is dominated by small glycine and alanine residues, aqueous solubility is generally favorable, though a trace of a mild acidic or organic co-solvent may be used to assist initial wetting if any material resists dissolving.
Reconstituted solutions should be prepared fresh where possible and kept cold during work. Peptides bearing acetylated N-termini and amidated C-termini are handled the same way as other synthetic peptides with respect to solvent contact: avoid repeated warming, protect from prolonged light exposure, and record the exact solvent and concentration used so that analytical results remain traceable. All preparation described here is for in-vitro laboratory characterization only.
Storage & stability
In lyophilized form, P-21 is most stable when stored sealed and desiccated at -20 °C, where it can be maintained for extended periods with minimal degradation; short-term storage at 2-8 °C is acceptable for material in active use. Once reconstituted, the peptide is less stable and should be held refrigerated and used promptly, or divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles that can promote aggregation or hydrolysis. Protect all material from moisture, heat, and direct light, and allow vials to equilibrate to room temperature before opening to prevent condensation.
How it's tested
Identity and purity of P-21 are verified analytically before release. Reversed-phase high-performance liquid chromatography (HPLC) is used to quantify purity, with this lot characterized at ≥99%, resolving the target peptide from process-related impurities and truncated sequences. Mass spectrometry (MS) confirms molecular identity by matching the observed mass of the acetylated, amidated hexapeptide against its expected value, corroborating both the sequence composition and the terminal modifications. A Certificate of Analysis (COA) documenting these results is available for each lot, providing traceable verification of identity and purity for research records.