Sermorelin and Tesamorelin compared

Sermorelin is the first 29 residues of growth hormone–releasing hormone as an amide. Tesamorelin is the full 44-residue amide with a trans-3-hexenoyl group on its N-terminus, so sermorelin's whole sequence is contained in it.

Sequences side by side

Sermorelin is a continuous stretch of Tesamorelin: 29 residues in common, aligned below by Tesamorelin's numbering. In each column the upper residue is Sermorelin's and the lower is Tesamorelin's. Positions outside the shorter sequence are dimmed.

Termini and bridges also differ: N-terminus: Sermorelin free amine, Tesamorelin N-(trans-3-hexenoyl).

Calculated properties

Calculated from each structure

Property	Sermorelin	Tesamorelin	Difference (Tesamorelin − Sermorelin)
Residues	29	44	+15
Molecular formula	C149H246N44O42S	C221H366N72O67S
Monoisotopic mass (Da)	3,355.8187	5,132.7166	+1,776.8979
Average mass (g/mol)	3,357.93	5,135.86	+1,777.92
Net charge at pH 7	4.0	4.0	0.0
Isoelectric point	10.95	11.43	+0.48
Hydropathy (GRAVY)	-0.22	-0.80	−0.58
ε280 (M−1 cm−1)	2,980	2,980

Telling them apart by mass spectrometry

The monoisotopic masses differ by 1,776.8979 Da, which any routine mass spectrometer resolves.

Expected protonated ions (monoisotopic m/z)

Ion	Sermorelin	Tesamorelin
[M+H]+	3,356.8260	5,133.7239
[M+2H]2+	1,678.9166	2,567.3656
[M+3H]3+	1,119.6135	1,711.9128
[M+4H]4+	839.9620	1,284.1864

Telling them apart by HPLC

They differ greatly in size (29 and 44 residues), so their reversed-phase retention cannot be estimated from average hydropathy; size, charge and the residues at the ends all contribute. They are usually well separated. Retention depends on the whole molecule and on the method, so the order is confirmed by running both, or by mass spectrometry of each peak.

Analytical variants each can form

The sequence-specific variants from each entry. A variant only one of them can form is a quick way to tell which is which, and a reminder of what to look for in each.

Sequence-specific variants

Variant	Mass change	Sermorelin	Tesamorelin
Methionine oxidation	+15.995 Da per oxidized residue	Yes	Yes
Asparagine deamidation	+0.984 Da	Yes	Yes
Glutamine deamidation	+0.984 Da	Yes	Yes
C-terminal amide	free-acid variant +0.984 Da	Yes	Yes

Full details, with isotope patterns and fragment ions, are on each entry: Sermorelin and Tesamorelin. Both are compared with the rest of their family on the family page.

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 and Tesamorelin compared. Cosmic Peptides Research Library. Retrieved October 26, 2026, from https://cosmicpeptides.com/research/peptides/compare/sermorelin-vs-tesamorelin

@misc{cosmicpeptides_research_peptides_compare_sermorelin_vs_tesamorelin,
  author       = {{Cosmic Peptides}},
  title        = {Sermorelin and Tesamorelin compared},
  howpublished = {Cosmic Peptides Research Library},
  year         = {2026},
  month        = oct,
  url          = {https://cosmicpeptides.com/research/peptides/compare/sermorelin-vs-tesamorelin},
  urldate      = {2026-10-26},
  note         = {Last reviewed 2026-10-25}
}

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