Sermorelin

The N-terminal 29 residues of growth hormone–releasing hormone, as the C-terminal amide. Every value on this page is calculated from the structure shown, by the method and constants in the sources below; measured values for a particular lot are on its certificate of analysis.

Structure

Three-letter code: 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 code: YADAIFTNSY RKVLGQLSAR KLLQDIMSR

• 29 residues
• N-terminus: free amine
• C-terminus: amide

Calculated properties

Calculated from the structure

Property	Value
Molecular formula	C149H246N44O42S
CAS Registry Number	86168-78-7
Average molecular weight	3,357.93 g/mol
Monoisotopic mass	3,355.8187 Da
Net charge at pH 7	4.0
Isoelectric point	10.95
Molar absorption coefficient, 280 nm	2,980 M−1 cm−1
Hydropathy (GRAVY)	-0.22

Net charge across the pH range

pH 2	pH 4	pH 6	pH 7	pH 8	pH 10	pH 12
6.0	4.9	4.0	4.0	3.8	1.9	-1.6

Composition: Leu 4, Ala 3, Arg 3, Ser 3, Asp 2, Gln 2, Ile 2, Lys 2, Tyr 2, Asn 1, Gly 1, Met 1, Phe 1, Thr 1, Val 1.

Expected mass spectrometry ions

The protonated ions expected in positive-mode electrospray, from the monoisotopic mass, and the common sodium and potassium adducts. MALDI spectra show mainly [M+H]⁺.

Expected ions (monoisotopic)

Ion	m/z
[M+H]+	3,356.8260
[M+2H]2+	1,678.9166
[M+3H]3+	1,119.6135
[M+4H]4+	839.9620
[M+5H]5+	672.1710
[M+Na]+	3,378.8079
[M+K]+	3,394.7819

Isotope pattern

Natural carbon-13, nitrogen-15, oxygen-18, sulfur-34 and deuterium spread each ion over a cluster of peaks about 1 Da apart (1/z on the m/z scale). For a molecule this size the monoisotopic peak is not the tallest: the most abundant is M+1. A spectrum read at its tallest peak, or a deconvoluted mass from it, sits about 1.00 Da above the monoisotopic mass.

Isotope peaks (relative abundance, most abundant = 100)

Peak	Abundance	Neutral mass	[M+H]+	[M+2H]2+	[M+3H]3+	[M+4H]4+	[M+5H]5+
M (monoisotopic)	54.8	3,355.8187	3,356.8260	1,678.9166	1,119.6135	839.9620	672.1710
M+1	100.0	3,356.8215	3,357.8288	1,679.4180	1,119.9478	840.2127	672.3716
M+2	97.9	3,357.8240	3,358.8313	1,679.9193	1,120.2820	840.4633	672.5721
M+3	67.7	3,358.8264	3,359.8336	1,680.4205	1,120.6161	840.7139	672.7725
M+4	36.8	3,359.8286	3,360.8358	1,680.9216	1,120.9501	840.9644	672.9730
M+5	16.6	3,360.8307	3,361.8380	1,681.4226	1,121.2842	841.2149	673.1734
M+6	6.5	3,361.8328	3,362.8401	1,681.9237	1,121.6182	841.4655	673.3738
M+7	2.2	3,362.8349	3,363.8421	1,682.4247	1,121.9522	841.7160	673.5742
M+8	0.7	3,363.8370	3,364.8442	1,682.9258	1,122.2863	841.9665	673.7747

Fragment ions (MS/MS)

Collision-induced fragmentation breaks peptide bonds along the backbone. Fragments that keep the N-terminus are b ions; those that keep the C-terminus are y ions. Reading the ladder confirms the sequence residue by residue. Singly charged monoisotopic values, with doubly charged values beside them. The b ion containing every residue is rarely seen and the y ion containing every residue is the precursor itself, so neither is listed.

b and y ions

b#	b+	b2+	Residue	y+	y2+	y#
1	164.0706	82.5389	Tyr	—	—	29
2	235.1077	118.0575	Ala	3,193.7626	1,597.3850	28
3	350.1347	175.5710	Asp	3,122.7255	1,561.8664	27
4	421.1718	211.0895	Ala	3,007.6986	1,504.3529	26
5	534.2558	267.6316	Ile	2,936.6615	1,468.8344	25
6	681.3243	341.1658	Phe	2,823.5774	1,412.2923	24
7	782.3719	391.6896	Thr	2,676.5090	1,338.7581	23
8	896.4149	448.7111	Asn	2,575.4613	1,288.2343	22
9	983.4469	492.2271	Ser	2,461.4184	1,231.2128	21
10	1,146.5102	573.7587	Tyr	2,374.3864	1,187.6968	20
11	1,302.6113	651.8093	Arg	2,211.3230	1,106.1652	19
12	1,430.7063	715.8568	Lys	2,055.2219	1,028.1146	18
13	1,529.7747	765.3910	Val	1,927.1270	964.0671	17
14	1,642.8588	821.9330	Leu	1,828.0585	914.5329	16
15	1,699.8802	850.4438	Gly	1,714.9745	857.9909	15
16	1,827.9388	914.4730	Gln	1,657.9530	829.4801	14
17	1,941.0229	971.0151	Leu	1,529.8944	765.4509	13
18	2,028.0549	1,014.5311	Ser	1,416.8104	708.9088	12
19	2,099.0920	1,050.0496	Ala	1,329.7784	665.3928	11
20	2,255.1931	1,128.1002	Arg	1,258.7412	629.8743	10
21	2,383.2881	1,192.1477	Lys	1,102.6401	551.8237	9
22	2,496.3722	1,248.6897	Leu	974.5452	487.7762	8
23	2,609.4562	1,305.2317	Leu	861.4611	431.2342	7
24	2,737.5148	1,369.2610	Gln	748.3770	374.6922	6
25	2,852.5417	1,426.7745	Asp	620.3185	310.6629	5
26	2,965.6258	1,483.3165	Ile	505.2915	253.1494	4
27	3,096.6663	1,548.8368	Met	392.2075	196.6074	3
28	3,183.6983	1,592.3528	Ser	261.1670	131.0871	2
29	—	—	Arg	174.1349	87.5711	1

Immonium ions (low-mass markers of the residues present): Gly 30.0338, Ala 44.0495, Ser 60.0444, Val 72.0808, Thr 74.0600, Ile 86.0964, Leu 86.0964, Asn 87.0553, Asp 88.0393, Gln 101.0709, Lys 101.1073, Met 104.0528, Phe 120.0808, Arg 129.1135, Tyr 136.0757.

What to watch for analytically

Variants this sequence can give, from its chemistry. They are what an HPLC or mass spectrometry result for this peptide is read against; none is a statement about a particular lot. Where synthesis variants come from is explained in How synthetic peptides are made.

Sequence-specific variants

Variant	Mass change	Why
Methionine oxidation	+15.995 Da per oxidized residue	Methionine at position 27 can oxidize to the sulfoxide, which usually elutes slightly earlier in reversed-phase HPLC.
Asparagine deamidation	+0.984 Da	Asparagine at position 8 can deamidate to aspartic or isoaspartic acid through a succinimide intermediate. Moisture, higher pH and warmth speed it up.
Glutamine deamidation	+0.984 Da	Glutamine at positions 16 and 24 can also deamidate, much more slowly than asparagine.
C-terminal amide	free-acid variant +0.984 Da	The C-terminus is an amide. The corresponding free acid, from synthesis or hydrolysis, differs by +0.984 Da, close to the isotope spacing, so it needs a resolved spectrum to tell apart.
Synthesis-related variants	e.g. +252.082 Da (Pbf), minus a residue (deletion)	As for any synthetic peptide, deletion sequences and incompletely deprotected forms can occur; on arginine, a residual Pbf protecting group adds 252.082 Da.

Sources & Further Reading

1. Prohaska T, Irrgeher J, Benefield J, Böhlke JK, Chesson LA, Coplen TB, et al. Standard atomic weights of the elements 2021 (IUPAC Technical Report). Pure and Applied Chemistry 2022;94(5):573–600. doi:10.1515/pac-2019-0603
2. Wang M, Huang WJ, Kondev FG, Audi G, Naimi S. The AME 2020 atomic mass evaluation (II). Tables, graphs and references. Chinese Physics C 2021;45(3):030003. doi:10.1088/1674-1137/abddaf
3. Rice P, Longden I, Bleasby A. EMBOSS: the European Molecular Biology Open Software Suite. Trends in Genetics 2000;16(6):276–277. doi:10.1016/S0168-9525(00)02024-2
4. Pace CN, Vajdos F, Fee L, Grimsley G, Gray T. How to measure and predict the molar absorption coefficient of a protein. Protein Science 1995;4(11):2411–2423. doi:10.1002/pro.5560041120
5. Kyte J, Doolittle RF. A simple method for displaying the hydropathic character of a protein. Journal of Molecular Biology 1982;157(1):105–132. doi:10.1016/0022-2836(82)90515-0
6. Meija J, Coplen TB, Berglund M, Brand WA, De Bièvre P, Gröning M, et al. Isotopic compositions of the elements 2013 (IUPAC Technical Report). Pure and Applied Chemistry 2016;88(3):293–306. doi:10.1515/pac-2015-0503
7. Roepstorff P, Fohlman J. Letter to the editors: proposal for a common nomenclature for sequence ions in mass spectra of peptides. Biomedical Mass Spectrometry 1984;11(11):601. doi:10.1002/bms.1200111109
8. Biemann K. Contributions of mass spectrometry to peptide and protein structure. Biomedical and Environmental Mass Spectrometry 1988;16(1–12):99–111. doi:10.1002/bms.1200160119
9. Geiger T, Clarke S. Deamidation, isomerization, and racemization at asparaginyl and aspartyl residues in peptides. Succinimide-linked reactions that contribute to protein degradation. Journal of Biological Chemistry 1987;262(2):785–794. doi:10.1016/S0021-9258(19)75855-4
10. Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharmaceutical Research 2010;27(4):544–575. doi:10.1007/s11095-009-0045-6
11. D'Hondt M, Bracke N, Taevernier L, Gevaert B, Verbeke F, Wynendaele E, et al. Related impurities in peptide medicines. Journal of Pharmaceutical and Biomedical Analysis 2014;101:2–30. doi:10.1016/j.jpba.2014.06.012

Cosmic Peptides. (2026, October 25). Sermorelin: peptide reference entry. Cosmic Peptides Research Library. Retrieved October 26, 2026, from https://cosmicpeptides.com/research/peptides/sermorelin

@misc{cosmicpeptides_research_peptides_sermorelin,
  author       = {{Cosmic Peptides}},
  title        = {Sermorelin: peptide reference entry},
  howpublished = {Cosmic Peptides Research Library},
  year         = {2026},
  month        = oct,
  url          = {https://cosmicpeptides.com/research/peptides/sermorelin},
  urldate      = {2026-10-26},
  note         = {Last reviewed 2026-10-25}
}

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AU  - Cosmic Peptides
TI  - Sermorelin: peptide reference entry
T2  - Cosmic Peptides Research Library
PB  - Cosmic Peptides
PY  - 2026
DA  - 2026/10/25
UR  - https://cosmicpeptides.com/research/peptides/sermorelin
Y2  - 2026/10/26
LA  - en
ER  -