Molecular Structure Explorer
P-21
Structure of the compound covered in this guide.
Verified structure pending review
Last reviewed: October 2026 · Cleared Peptides research team
Research use only. P-21 (P021): Research Guide is supplied for laboratory research. It is not a drug, food, cosmetic, or dietary supplement. It is not FDA-approved. It is not for human or veterinary administration. This page does not give a dose or a method of administration. A study cited on this page describes that study’s own test article. It does not make this lot an approved medicine. To check a fact, open the PubMed or DOI link, confirm the authors and year, and match the paper’s compound name, CAS number, or sequence to the specification table. The full method is on the research desk page. Identity and purity for a lot are only what that lot’s certificate of analysis reports. An HPLC percentage is not a sterility result and not an endotoxin result unless the certificate prints those tests.
P-21 (P021) is a small peptidomimetic derived from an active region of ciliary neurotrophic factor (CNTF) and modified with an adamantylated glycine to improve stability. It was developed for laboratory research on neurotrophic signaling.
P-21 Structure and Identifiers
| Name | P-21 |
|---|---|
| Synonyms | P021 |
| Origin | CNTF-derived tetrapeptide with adamantane-modified glycine |
| CAS number | Not available. No public CAS Registry Number was found in the sources reviewed for this guide. |
| Identity | Confirmed per lot COA |
| Form | Powder |
Design
Full-length neurotrophic proteins such as CNTF are large and unstable. P-21 condenses a CNTF-derived epitope into a small, protease-resistant molecule, a common approach in peptidomimetic research.
Published Research Areas
- Neurogenesis and neurotrophic-signaling studies in laboratory models
- Comparison with other neurotrophic tool compounds such as Dihexa and Cerebrolysin
This summary describes laboratory research only and makes no claim about effects in humans or animals.
Purity Testing and Storage
Every lot of P-21 supplied by Cleared Peptides is tested by an independent laboratory for identity and purity (or composition, for multi-component preparations), and the lot Certificate of Analysis is published on our COA page. Store P-21 sealed at −20 °C, dry and protected from light. Handle according to your institution’s chemical-hygiene procedures.
Analytical testing notes for P-21
P-21 is identified in this guide as CAS Not available. No public CAS Registry Number was found in the sources reviewed for this guide.. An identity test compares a measurement with those values. A mass spectrum is the usual measurement for a peptide. FTIR, when a certificate uses it, is a supporting infrared fingerprint and is less specific for closely related sequences.
For P-21, routine chemical characterization is reversed-phase HPLC for area-percent purity and mass spectrometry for identity against the formula and mass in the table above. Oxidizable residues (cysteine, methionine, tryptophan) and deamidating residues (asparagine, glutamine), when the sequence contains them, are typical related-impurity questions for the chromatogram and the mass spectrum.
HPLC purity for this material is an area-percent result at the wavelength and gradient the laboratory states, commonly ultraviolet detection near 214 nm on a reversed-phase column. The instrument is a gradient pump, injector, column oven, and UV or diode-array detector. That percentage is not the number of milligrams in the vial. Water, acetate, trifluoroacetate, and other UV-silent material can dominate the gross weight while the purity figure stays high. Net peptide content, from an assay or amino-acid analysis, is the separate result to read when the certificate reports it.
A sterility test and an endotoxin test are not included in a chemical purity result. The compendial sterility test is a culture method (USP <71>): membrane filtration or direct inoculation into fluid thioglycollate medium and soybean-casein digest medium, incubated for 14 days. A PCR sterility screen uses a thermal cycler to detect microbial DNA and is a different method. The endotoxin test (USP <85> LAL, or USP <86> recombinant Factor C) reports endotoxin units with an incubating reader or a cartridge reader. Use a result only when that method is printed on the lot certificate. One published example in this catalog states that the report does not cover microbial contamination or endotoxins. The full description of equipment, standards, and how US laboratory accreditation works is in peptide analytical testing. Lot records are on the COA page.
Frequently Asked Questions
What is P-21 derived from?
From an active region of ciliary neurotrophic factor (CNTF).
Is P-21 for human use?
No. Cleared Peptides supplies P-21 for laboratory research use only; it is not for human or veterinary use.
Selected References
A public CAS Registry Number was not found for P-21 (also called P021), a CNTF-derived tetrapeptide described with an adamantane-modified glycine. Identity for each lot is the batch COA. Papers that discuss this peptide in disease models are not summarized here, because this site does not restate treatment or benefit claims.
Laboratory note: solubility depends on salt form and solvent. This guide does not state a single solubility figure. Handling of lyophilized material is described in the peptide storage guide.
Research Use Only Notice
This guide is provided for educational and laboratory reference purposes. It summarizes published, primarily in-vitro and structural research literature and does not describe, recommend or imply any use in humans or animals. Products sold by Cleared Peptides are for laboratory research use only; they are not drugs, foods, cosmetics or dietary supplements, are not FDA-approved, and are not intended to diagnose, treat, cure, mitigate or prevent any disease. No dosing, administration or therapeutic information is provided.
