Palmitoyl Tetrapeptide-7

1 Identity

Acylated cosmetic tetrapeptide (lipopeptide conjugate). A synthetic tetrapeptide Gly-Gln-Pro-Arg carrying a single C16:0 palmitoyl group amide-bonded to the N-terminal alpha-amino group of Gly1. Metal-free, non-sulfur-containing, no cysteine, no disulfide, no chromophore stronger than the amide bond. Sold as a topical bulk cosmetic ingredient and laboratory raw material. and CAS 221227-05-0. A second INCI name for the same molecule is in live commerce: one reagent catalog lists this article as 'Palmitoyl Tetrapeptide-3 (Palmitoyl Tetrapeptide-7)' under the identical CAS 221227-05-0, so a purchase order written against either INCI number can be filled from the same drum.

Sequence

N-hexadecanoyl(palmitoyl)-Gly-L-Gln-L-Pro-L-Arg-OH (Pal-GQPR). One C16:0 palmitoyl group amide-bonded to the alpha-amino group of Gly1; free C-terminal carboxylic acid on Arg4; no amidation, no cyclization, no disulfide. Glycine is achiral; Gln, Pro and Arg are L and proteinogenic. The sequence statement is incomplete without the regiochemistry statement: the arginine guanidino group and the glutamine side-chain amide are competing acylation sites, the attachment point is carried nowhere in the mass, and the article is specifically the N-alpha-palmitoyl regioisomer.

Molecular formula

C34H62N8O7 for the neat conjugate. Free tetrapeptide GQPR C18H32N8O6. The article is also sold as parts-per-million dilutions in glycerin/water and in butylene glycol carriers, which have no formula at all and must not be received against this specification. Four independent reagent catalogs index CAS 221227-05-0 to Pal-Gly-Gln-Pro-Arg-OH and the formula reconstructs exactly from the sequence - two independent routes agreeing to the digit.

Average mass

694.919 Da (C34H62N8O7) on IUPAC 2021 abridged conventional atomic weights (C 12.011, H 1.008, N 14.007, O 15.999). A reagent catalog prints 694.91 for the same formula on the older table, and the two agree within rounding; the basis is stated on the face of the number because this catalog standardizes on the 2021 table. The formula reconstructs from sequence alone on the same basis that reproduces, to the digit, every other formula printed for this group - palmitoyl pentapeptide-4 C39H75N7O10, palmitoyl tripeptide-5 C33H65N5O5, palmitoyl tripeptide-1 C30H54N6O5, the 24-residue IGF-1 Ec peptide C121H199N41O40 and the Khavinson-family peptides. Free tetrapeptide GQPR 456.504, exactly 238.42 Da lighter, which is the palmitoyl delta and the same delta that separates Pal-GHK from GHK.

Monoisotopic mass

694.47415 Da neutral (C34H62N8O7); [M+H]+ 695.48143; [M+2H]2+ m/z 348.24435; [M-H]- 694.46687. Identity window on [M+H]+ at plus or minus 5 ppm is plus or minus 0.0035 Da. Free tetrapeptide GQPR 456.24448 neutral, [M+H]+ 457.25176. The C-terminal amide is 693.49013 neutral, 0.984 Da below parent and unresolved below about 30,000 resolving power.

Salt / variant note

(1) des-palmitoyl free tetrapeptide GQPR, C18H32N8O6, 456.504 / 456.24448, [M+H]+ 457.25176 - the incomplete-acylation failure and the cheapest substitution, 238.42 Da light. Blended with free palmitic acid (256.42 average) it gives a plausible elemental analysis and a correct appearance while the spectrum shows two peaks and no conjugate. (2) regioisomers carrying no mass difference: N-guanidino-acylated and Gln-side-chain-acylated species are all C34H62N8O7 at 694.919 and 694.47415, and only MS/MS fragmentation or co-elution against a qualified standard separates them from the N-alpha article. (3) acyl-chain axis: myristoyl (C14:0) analogue C32H58N8O7 666.865 / 666.44285, 28.05 Da light; stearoyl (C18:0) analogue C36H66N8O7 722.973 / 722.50545, 28.05 Da heavy. Both arise from fatty-acid feedstock that is not a single chain length. (4) glutamine deamidation to Pal-GEPR, C34H61N7O8, 695.903 / 695.45816 - plus 0.984 Da, the mirror image of the amide artifact and a genuine storage degradant on a Gln-containing peptide. (5) C-terminal amide C34H63N9O6, 693.935 / 693.49013 - 0.984 Da below the free acid, invisible below about 30,000 resolving power. (6) same-shelf confusables, all sold by the same sellers at the same 200 mg size: palmitoyl tripeptide-1 578.799, Pal-AHK 592.826, palmitoyl tripeptide-5 611.913, palmitoyl tripeptide-38 675.971, palmitoyl pentapeptide-4 802.068. (7) name axis, and the one that actually moves goods: the same CAS is cataloged under two INCI numbers, tetrapeptide-3 and tetrapeptide-7, so a certificate headed with the other number is not on its face wrong; and separately 'Matrixyl 3000' is a blend of this ingredient with palmitoyl tripeptide-1 in a glycerin/water carrier, not a synonym for either - a certificate for the blend presented against an order for the neat conjugate states no peptide loading at all and is the commonest failure on this article. (8) presentation axis: neat conjugate powder against parts-per-million carrier dilutions, which are a different article of trade with a different specification.

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, belongs to other molecules, and is kept separate on this page: Kraeling et al., Cutan Ocul Toxicol 2015, PMID 24754410, in vitro, excised human cadaver and hairless guinea pig skin; Choi et al., Biomol Ther 2014, PMID 25143811, in vitro, hairless mouse skin; Imhof and Leuthard, Dermatology 2021, PMID 32882685, systematic review of over-the-counter topical antiaging agents; Wang et al., Adv Sci 2025, PMID 39783908, solubility and delivery of palmitoylated cosmetic peptides; Chen et al., World J Clin Cases 2021, PMID 33748252, case report on injection of a cosmetic peptide. 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. Literature volume by study type is printed at the head of the research page so a reader sees the size of the base before reading a word of it.

4 Storage & specification

Storage

Off-white to pale-tan waxy lyophilized powder or friable solid, 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 arginine-bearing conjugate is hygroscopic and the jar is equilibrated to room temperature sealed 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 and recorded on the lot record. The palmitoyl chain makes the conjugate amphiphilic and poorly water-soluble - the solubility limitation documented for palmitoylated cosmetic peptides generally at PMID 39783908 - so dissolution for assay uses a named co-solvent system stated on the handling page, which says nothing about 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 this 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, des-palmitoyl GQPR and the deamidated Pal-GEPR species at plus 0.984 Da - not total assay: amide hydrolysis at the acyl linkage regenerates the free tetrapeptide and free palmitic acid, Gln deamidation drifts slowly, and both are 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. The interval is shortened on data and is never extended without a completed dataset.