Sermorelin

1 Identity

Synthetic linear 29-residue peptide amide corresponding to residues 1-29 of human growth-hormone-releasing hormone, the N-terminal fragment of the 44-residue endogenous peptide. All residues proteinogenic and L-configured; no acylation, no non-proteinogenic residue, no cysteine, no disulfide. One methionine at position 27 and one asparagine at position 8 are the degradation-relevant residues. The C-terminal amide is a structural feature and not a detail: the free-acid 29-mer is a different compound, 0.98 Da heavier, and the two are indistinguishable on a nominal-mass instrument. and Geref and Geref Diagnostic. CAS 86168-78-7 for the free base and CAS 516482-86-3 for the acetate — two registry numbers for one molecular entity, which is why a purchaser matching on CAS alone concludes they are two compounds. PubChem CID 16132413. One institutional supplier catalogs the same entity under the name 'Growth Hormone Releasing Factor Fragment 1-29 amide human'.

Sequence

H-Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-NH2; one-letter YADAIFTNSYRKVLGQLSARKLLQDIMSR-NH2, 29 residues, C-terminally amidated. Supplied lyophilized as the acetate salt. Met27 oxidizes to the sulfoxide; Asn8 deamidates to a mixture of Asp and isoAsp.

Molecular formula

C149H246N44O42S (free base). One sulfur, in the Met27 thioether. The presence of that single sulfur is a positive identity test against the commonest substitute, which has none.

Average mass

3357.933 Da (C149H246N44O42S) on IUPAC 2021 abridged conventional atomic weights. PubChem publishes 3357.9 and so does a reagent catalog; the same formula on the pre-2021 table returns 3357.882, so the published rounding covers both bases. The acetate salt has no single average mass: at 1 mol acetate the formula weight is 3417.99 (acetate 1.76 percent w/w), at 2 mol 3478.04 (3.45 percent), at 3 mol 3538.09 (5.09 percent). The seller writes its own acetate article as C149H246N44O42S - XC2H4O2 and declines to assign X, which is the correct way to state it and the way this catalog states it.

Monoisotopic mass

3355.81870 Da neutral free base; [M+H]+ 3356.82598; [M+3H]3+ 1119.61351; [M+4H]4+ 839.96195 (monoisotopic). A plus or minus 5 ppm window on the protonated ion is plus or minus 0.017 Da, which is smaller than the 0.98 Da amide-versus-acid difference and therefore sufficient to see it, but is not sufficient to identify which of the two isobaric +0.98 defects has occurred; that determination requires chromatography and a peptide map and cannot be made from mass at any resolution.

Salt / variant note

The richest substitution field in the catalog, and the arithmetic is unusually treacherous. (1) GHRH(1-29) free acid, the des-amido compound, C149H245N43O43S, 3358.917 avg / 3356.80271 mono — exactly +0.98 Da. (2) Asn8-deamidated sermorelin, Asn converted to Asp or isoAsp, also +0.98 Da at 3358.917 avg / 3356.80271 mono. Those two lines are the trap: the des-amide free acid and the Asn8-deamidated amide carry the same mass shift to five decimal places, so intact mass at any resolution cannot tell you which defect is in the vial; only chromatographic resolution of the Asp and isoAsp forms plus peptide mapping distinguishes them, and isoAsp is chromatographically stubborn. (3) Modified GRF(1-29), sold as 'Mod GRF 1-29' or 'CJC-1295 without DAC', [D-Ala2, Gln8, Ala15, Leu27]-GHRH(1-29)-NH2, C152H252N44O42, 3367.954 avg / 3365.89358 mono: ten daltons heavier on a 3.4 kDa molecule, and it is the cheaper and more widely stocked article, which makes it the substitution to expect. Two clean discriminators exist — it contains no sulfur at all, because Met27 is replaced by Leu27, so it has no sulfoxide degradant and no 34S contribution to its isotope envelope; and it carries a D-amino acid at position 2, so a Marfey or chiral screen separates it even where the mass does not. (4) CJC-1295 with DAC, C165H269N47O46, 3647.250 avg / 3645.01548 mono, +289.3. (5) Met27 sulfoxide, +15.995: C149H246N44O43S, 3373.932 avg / 3371.81361 mono; Met27 sulfone, +31.990: C149H246N44O44S, 3389.931 avg / 3387.80853 mono. (6) Salt forms traded under the bare name: the reagent-catalog article IS the acetate and the supplier writes the stoichiometry as X; 1 mol acetate is 1.76 percent w/w of the salt, 2 mol 3.45 percent, 3 mol 5.09 percent; 1 mol trifluoroacetate 3.28 percent, 2 mol 6.36 percent. An institutional supplier's free-base listing and a reagent catalog's acetate listing are the same molecular entity under two names and two counter-ion conventions. (7) Blends: the consumer channel sells sermorelin as a component of fixed-ratio GHRP-2 and GHRP-6 blends at least as often as it sells it alone, and a blend certificate reports the blend, not this molecule. (8) Single-residue deletion sequences are the dominant impurity class, and the correct window for this sequence is 57.05 Da, loss of Gly15, to 163.17 Da, loss of Tyr1 or Tyr10, the tyrosine residue mass on the IUPAC 2021 table being 163.176. A 71-to-186 Da range circulates for this purpose and is wrong at both ends for this sequence, since the sequence contains glycine at position 15 and contains no tryptophan at all.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

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

Human evidence exists and it is old and narrow, and it belongs to the approved finished dosage forms rather than to bulk material. The principal approval-era study is Thorner and colleagues, a multicenter open-label study in 110 previously untreated prepubertal children with growth-hormone deficiency, 86 evaluable, 30 micrograms per kilogram subcutaneously nightly (PMID 8772599). Around it sits diagnostic-testing work from the late 1980s and 1990s in support of the Geref applications, plus a rodent and in-vitro GHRH-analogue literature. What does not exist is a contemporary controlled trial supporting the uses for which compounded sermorelin is currently prescribed: the study most often cited for that purpose, Corpas and colleagues 1992, ran 14 days per dose arm in 10 men and did not measure body composition at all — its closing sentence proposed a hypothesis that has not been tested to completion in the 34 years since. No FDA-registered trial is recruiting under this name. The citation index page presents the approval-era trials with study-type badges and the studied population stated on the face of each entry, and records that a discontinued approval is a historical fact about a finished dosage form rather than evidence about bulk material.

4 Storage & specification

Storage

Lyophilized white powder in amber Type I glass, bromobutyl stopper, nitrogen headspace, desiccant in the shipper. Labeled condition: store at -20 degrees C plus or minus 5 degrees C, desiccated, protected from light. This peptide adsorbs to glass and plastic at low concentration, so container-closure qualification includes a measured recovery check on the actual vial and stopper combination rather than an assumption carried over from another product. Vials equilibrated to room temperature before opening. Shipped on dry ice or in a validated shipper holding not more than 8 degrees C for transit up to 96 hours with a single-use temperature logger in every shipper.

Shelf life

Provisional 24-month retest interval at -20 degrees C plus or minus 5 degrees C, desiccated, reduced to a provisional 12 months if only 2-8 degrees C storage can be evidenced across the whole chain. Provisional pending this company's stability program, which for this molecule trends methionine sulfoxide and total deamidated species as the two attributes most likely to move first and sets the retest date from whichever reaches its limit sooner. Pulls at 0, 3, 6, 12, 18, 24 and 36 months at the labeled condition with a parallel 12-month arm at 2-8 degrees C.