Pal-GHK / Palmitoyl Tripeptide-1

1 Identity

Acylated cosmetic tripeptide (lipopeptide conjugate). A synthetic tripeptide Gly-His-Lys - a sequence that occurs in human plasma and in the alpha-2(I) chain of type I collagen - bearing a single C16:0 palmitoyl group amide-bonded to the N-terminal alpha-amino group. Metal-free by specification: this article is not a copper complex, and any copper detected is a deviation, not a grade. Sold as a topical bulk cosmetic and laboratory raw material. and CAS 147732-56-7 as commonly indexed. Not a synonym, and a separate article with a separate mass: GHK-Cu, the copper complex of the free tripeptide, which is the molecule that holds FDA's Category 1 listing (except for injectable routes) and to which most of the 'copper peptide' literature belongs.

Sequence

N-hexadecanoyl(palmitoyl)-Gly-L-His-L-Lys-OH (Pal-GHK). A single C16:0 palmitoyl group is amide-bonded to the alpha-amino group of Gly1; free C-terminal carboxylic acid on Lys3; no amidation, no cyclization, no disulfide; glycine is achiral and His and Lys are L and proteinogenic. The sequence statement is incomplete without the regiochemistry statement: the lysine epsilon-amine and the histidine imidazole nitrogens are competing acylation sites, the attachment point is not carried in the mass, and the article is specifically the N-alpha-palmitoyl regioisomer. Metal content is a specification attribute, not an assumption: the article is the metal-free conjugate, and copper is a named ICP-MS limit on every lot rather than a grade.

Molecular formula

C30H54N6O5. Free ligand GHK C14H24N6O4. The 1:1 deprotonated copper complex, which is a different article, would be C30H52N6O5Cu. The formula reconstructs exactly from Pal-Gly-His-Lys, and catalog tables that enumerate this molecule as a confusable print the same C30H54N6O5 with 578.79 average, 578.4156 monoisotopic and [M+H]+ 579.4228 - two independent routes agreeing to the digit.

Average mass

578.799 Da (C30H54N6O5) on IUPAC 2021 abridged conventional atomic weights. Listings commonly print 578.79 for the same formula on the older atomic weights, and the two agree within rounding. The collision that matters: P021 (CAS 1246751-68-7) has average mass 578.67 - 0.13 Da away - and at least one live seller listing prints C30H54N6O5, this article's exact formula, as the formula of P021. Two different articles in this same catalog sit inside a tenth of a dalton of one another at average mass, and a certificate that reports 'MW 578.8' with no ion and no decimals distinguishes neither. Free ligand GHK 340.38, exactly 238.42 Da lighter. Pal-AHK 592.83, exactly 14.03 Da heavier. 1:1 copper complex 640.33.

Monoisotopic mass

578.41557 Da neutral (C30H54N6O5); [M+H]+ 579.42285; [M+2H]2+ m/z 290.21506; [M-H]- 578.40829. Identity window on [M+H]+ at plus or minus 5 ppm is plus or minus 0.0029 Da. P021 at the same nominal mass is 578.30641 neutral, [M+H]+ 579.31369 - 0.109 Da and 189 ppm away, which is resolved at 30,000 resolving power and invisible below it. Free ligand GHK 340.18590 neutral, [M+H]+ 341.19318. Pal-AHK 592.43122 neutral. 1:1 deprotonated copper complex C30H52N6O5Cu 639.32954 neutral, and copper's 63/65 isotope pattern at roughly 69:31 makes a copper-bearing lot unmistakable on any spectrum already acquired.

Salt / variant note

(1) free ligand GHK / tripeptide-1, C14H24N6O4, 340.38 / 340.18590, [M+H]+ 341.19318 - the des-palmitoyl failure, 238.42 Da light. Blended with free palmitic acid (256.42 average) it gives a plausible elemental analysis and a correct appearance while the mass spectrum shows two peaks and no conjugate. Sold separately at 200 mg and at 50 mg on the same shelves. (2) GHK-Cu, the copper complex of that free ligand - a different substance, a different panel, and the holder of the only permissive FDA listing in this family; its literature and its regulatory status do not transfer to this article, which is routinely grouped with the copper peptides and is not one. (3) PAL-AHK, C31H56N6O5, 592.83 / 592.43122 - one methylene heavier, 14.03 Da, sold by the same sellers at the same 200 mg size and at the same list price. (4) P021, C27H42N6O8, 578.67 average / 578.30641 monoisotopic - a completely unrelated adamantane-capped tetrapeptide that sits 0.13 Da away at average mass and 0.109 Da away monoisotopically, and whose live seller listing prints this article's formula. (5) palmitoyl pentapeptide-4, C39H75N7O10, 802.07 / 801.55754 - the other article the loose INCI term 'Palmitoyl Oligopeptide' has been applied to, which is how an order written that way gets filled with the wrong molecule in good faith; that term is a trade mislabeling, not an identity, and it is never accepted as an identity statement on an incoming certificate. (6) REGIOISOMERS, carrying NO mass difference: N-epsilon-palmitoyl GHK and the imidazole-acylated species are all C30H54N6O5 at 578.80, and only MS/MS fragmentation or co-elution against a qualified standard separates them from the N-alpha article. (7) acyl-chain axis: myristoyl (C14:0) analogue C28H50N6O5 550.75, 28.05 Da light; stearoyl (C18:0) analogue C32H58N6O5 606.85, 28.05 Da heavy. (8) C-terminal amide C30H55N7O4, 577.82 / 577.43156 - 0.98 Da below the free acid and invisible below about 30,000 resolving power. (9) presentation axis, where the substitution actually happens: 'palmitoyl tripeptide-1' is sold both as neat conjugate powder and as parts-per-million dilutions in butylene glycol and water, and a certificate for the dilution presented as a certificate for the neat conjugate states no peptide loading at all.

2 Class & testing panel

Form

Single article

Testing panel

P2 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

No compound-specific primary literature has been located for this article under its own name - in vitro, animal or human - in cosmeceutical peptide reviews, in Cosmetic Ingredient Review safety assessments or in targeted searches on the INCI name. What exists is class-level and belongs to other molecules, and this page keeps it separate: the delivery literature, Kraeling et al., Cutan Ocul Toxicol 2015, PMID 24754410 (in vitro, excised human cadaver and hairless guinea pig skin) and Choi et al., Biomol Ther 2014, PMID 25143811 (in vitro, hairless mouse skin), which measure where cosmetic peptides go and which establish that palmitoylation is what makes a hydrophilic short peptide recoverable from skin layers at all; the systematic review of over-the-counter topical antiaging agents, Imhof and Leuthard, Dermatology 2021, PMID 32882685; the solubility and delivery citation for palmitoylated cosmetic peptides, Wang et al., Adv Sci 2025, PMID 39783908; and the injection-hazard case report, Chen et al., World J Clin Cases 2021, PMID 33748252. The GHK-Cu literature is about a different molecule and does not transfer to this one; that transfer is a known pattern of borrowed credibility in this market. No human trial of this article has been located and no registry number is quoted because none was found - an absence of located evidence rather than a demonstration that none exists. The Cosmetic Ingredient Review has published safety assessments for other peptide ingredients; none has been located for this one.

4 Storage & specification

Storage

Off-white to pale-tan lyophilized powder, acetate salt, packed in amber glass with a nitrogen headspace and a desiccant sachet. This is a laboratory and cosmetic raw-material presentation: non-sterile, no sterility claim, no stoppered-and-crimped injection format. Labeled condition 2-8 degrees C, protected from light and moisture; the material is hygroscopic and is equilibrated to room temperature in the sealed jar before opening so that atmospheric moisture does not condense onto the powder. Shipped ambient with a temperature-excursion indicator; excursions to 25 degrees C for up to 14 days cumulative are accepted against the stability protocol. The palmitoyl chain makes the conjugate amphiphilic and poorly water-soluble - the same limitation documented for palmitoylated cosmetic peptides generally (PMID 39783908) - so dissolution for assay uses a named co-solvent system, stated on the handling page, which says nothing about administration, route or vehicle.

Shelf life

Provisional 24-month retest interval at 2-8 degrees C, and provisional 36 months at -20 degrees C plus or minus 5 degrees C for the retained reference portion. Both are provisional placeholders for the company's own ICH Q1A-format study on three production lots, long-term at 5 degrees C plus or minus 3 degrees C and accelerated at 25 degrees C / 60 percent RH, which replaces them at the 12-month data point. The stability-indicating attributes are free palmitic acid and des-palmitoyl GHK, not total assay: amide hydrolysis at the acyl linkage regenerates the free tripeptide and free palmitic acid, and a slow drift there is invisible inside an unspecified-impurity bucket. A retest date is printed on every jar and first-expiry-first-out is enforced against that date rather than against receipt date.