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Molecular Weight Table

Comprehensive molecular weight data for all peptides in the AMP Peptide Research Database, including monoisotopic mass, average mass, calculated m/z values for common charge states, and adducts. Designed for LC-MS method development, quality control verification, and analytical method validation.

🔬 Introduction

Molecular weight (MW) is a fundamental parameter for peptide identification and quality control. This table provides monoisotopic masses (calculated from the most abundant isotope of each element) and average masses (weighted by natural isotopic abundance) for each peptide, along with the expected m/z values for common charge states observed in electrospray ionization mass spectrometry (ESI-MS).

Key Definitions

Term Definition
Monoisotopic Mass Mass calculated using the most abundant isotope of each element (¹H, ¹²C, ¹⁴N, ¹⁶O, ³²S)
Average Mass Mass calculated using the average atomic weight for each element (accounting for natural isotope distribution)
(M+H)+ Singly protonated ion — typically observed for small peptides (< 2000 Da)
(M+2H)²+ Doubly protonated ion — dominant for medium peptides (1000–4000 Da)
(M+3H)³+ Triply protonated ion — common for larger peptides (> 3000 Da)
(M+H+Na)²+ Sodium adduct ion — often observed as a minor species
(M-H)- Singly deprotonated ion (negative mode ESI)

1. Neurocognitive Peptides

Peptide Formula Monoisotopic MW Average MW (M+H)+ (M+2H)²+ (M+Na)+ (M-H)-
Semax C₃₇H₅₃N₉O₁₀S 703.37 706.83 704.37 352.69 726.35 702.37
Selank C₃₃H₅₇N₁₁O₉ 751.43 756.89 752.43 376.72 774.41 750.43
Noopept C₁₇H₂₂N₂O₄ 342.16 342.39 343.16 171.58 365.14 341.16
Cerebrolysin N/A (mixture) — — Variable Variable — —

Cerebrolysin Note

Cerebrolysin is a peptide cocktail with MW components ranging from ~120–10,000 Da. Major peptide clusters observed at m/z 500–1500 (MS), with characteristic fragmentation patterns used for fingerprint identification.

2. Sleep & Pineal Peptides

Peptide Formula Monoisotopic MW Average MW (M+H)+ (M+2H)²+ (M+Na)+ (M-H)-
Epitalon C₁₄H₂₂N₄O₉ 374.14 375.35 375.14 188.07 397.12 373.14
Pinealon C₁₅H₂₆N₆O₈ 418.18 431.41 419.18 210.09 441.16 417.18

3. Growth & Signaling Peptides

Peptide Formula Monoisotopic MW Average MW (M+H)+ (M+2H)²+ (M+3H)³+ (M+Na)+
MK-677 (free base) C₂₇H₃₆N₄O₅S 528.24 528.67 529.24 265.12 — 551.22
Ipamorelin C₃₈H₄₉N₉O₅ 711.38 711.86 712.38 356.69 — 734.36
GHRP-2 C₄₅H₅₄N₁₂O₆ 786.42 786.93 787.42 394.21 — 809.40
GHRP-6 C₄₆H₅₆N₁₂O₆ 800.43 801.00 801.43 401.22 — 823.41
CJC-1295 (without DAC) C₁₅₂H₂₅₂N₄₄O₄₂ 3313.9 3315.74 3314.9 1657.46 1105.31 3336.9
Sermorelin C₁₅₃H₂₅₃N₄₅O₄₂S 3354.91 3357.86 3355.91 1678.46 1119.31 3377.89

CJC-1295 Note

CJC-1295 is commonly synthesized with Drug Affinity Complex (DAC). The table above shows the unmodified 30-mer peptide. With DAC (CJC-1295 DAC), the MW is approximately 3380–3400 Da (C-terminal Lys modification with maleimide-DAC).

4. GLP-1 Receptor Agonists

Peptide Formula Monoisotopic MW Average MW (M+H)+ (M+3H)³+ (M+4H)⁴+ (M+5H)⁵+
Tirzepatide C₂₂₅H₃₄₈N₄₈O₆₈ 4807.54 4813.5 4808.54 1603.51 1202.89 962.51
Retatrutide C₂₂₉H₃₅₆N₅₀O₆₈ 4865.58 4872.5 4866.58 1622.86 1217.40 974.12
Semaglutide C₁₈₇H₂₉₁N₄₅O₅₉ 4107.10 4113.6 4108.10 1369.70 1027.53 822.22

5. Cosmetic & Topical Peptides

Peptide Formula Monoisotopic MW Average MW (M+H)+ (M+2H)²+ (M+Na)+ Notes
GHK (free base) C₁₄H₂₃N₆O₄ 339.18 339.36 340.18 170.59 362.16 Without Cu²⁺
GHK-Cu (complex) C₁₄H₂₁N₆O₄Cu 340.09 340.78 341.09 171.05 363.07 With Cu²⁺
Matrixyl (Pal-KTTKS) C₅₁H₈₉N₇O₁₂ 1063.66 1064.36 1064.66 532.83 1086.64 Palmitoylated
Argireline (Ac-EEMQRR-NH₂) C₃₈H₆₃N₁₁O₁₃ 884.46 888.07 885.46 443.23 907.44 Acetylated + amidated
SNAP-8 (Ac-EEMQRR-NH₂ 8aa) C₄₇H₇₉N₁₃O₁₅ 1069.58 1072.28 1070.58 535.79 1092.56 Acetylated + amidated

6. Tissue Repair & Regenerative Peptides

Peptide Formula Monoisotopic MW Average MW (M+H)+ (M+2H)²+ (M+3H)³+ (M+Na)+
BPC-157 C₆₂H₉₈N₁₆O₂₂ 1414.70 1419.58 1415.70 708.35 472.57 1437.68
TB-500 (Thymosin β₄ fragment) C₁₉₈H₃₀₆N₅₆O₆₅S₂ 4957.24 4963.54 4958.24 2479.62 1653.42 4980.22

7. Mitochondrial & Metabolic Peptides

Peptide Formula Monoisotopic MW Average MW (M+H)+ (M+2H)²+ (M+3H)³+ (M+4H)⁴+
MOTS-c C₁₀₀H₁₆₀N₂₆O₂₇ 2168.20 2174.49 2169.20 1085.10 723.73 543.05
SS-31 (Elamipretide) C₂₈H₄₇N₇O₇ 593.35 639.78 594.35 297.68 — —
Humanin C₁₁₉H₂₀₀N₃₄O₃₂S 2682.49 2687.10 2683.49 1342.25 895.17 671.63
AOD-9604 C₇₈H₁₂₂N₂₀O₂₄S 1810.87 1815.10 1811.87 906.44 604.63 —

📐 Mass Calculation Guide

For Method Development

Use the following m/z ranges for selected ion monitoring (SIM):

Peptide Size Primary Charge State Typical m/z Range
< 1000 Da (M+H)+ 300–1000
1000–3000 Da (M+2H)²+ 500–1500
3000–5000 Da (M+3H)³+ or (M+4H)⁴+ 800–1700
> 5000 Da (M+5H)⁵+ to (M+10H)¹⁰+ 500–2000

Calculating Expected m/z

For a peptide of mass M, the m/z of charge state z is:

m/z = (M + z × 1.007276) / z

Where: - M = neutral monoisotopic mass (Da) - z = number of charges - 1.007276 = mass of a proton (Da)

Example

For Semax (M = 703.37 Da): - (M+H)+: (703.37 + 1.007) / 1 = 704.38 - (M+2H)²+: (703.37 + 2.015) / 2 = 352.69 - (M+Na)+: (703.37 + 22.989) / 1 = 726.36

📊 Summary Table: 25 Peptides Sorted by MW

# Peptide Monoisotopic MW (Da) Average MW (Da) Best m/z for SIM Recommended Mode
1 GHK-Cu 340.09 340.78 341.09 (M+H)+ ESI+
2 Noopept 342.16 342.39 343.16 (M+H)+ ESI+
3 Epitalon 374.14 375.35 375.14 (M+H)+ ESI+
4 Pinealon 418.18 431.41 419.18 (M+H)+ ESI+
5 MK-677 528.24 528.67 529.24 (M+H)+ ESI+
6 SS-31 593.35 639.78 594.35 (M+H)+ ESI+
7 Semax 703.37 706.83 352.69 (M+2H)²+ ESI+
8 Ipamorelin 711.38 711.86 356.69 (M+2H)²+ ESI+
9 Selank 751.43 756.89 376.72 (M+2H)²+ ESI+
10 GHRP-2 786.42 786.93 394.21 (M+2H)²+ ESI+
11 GHRP-6 800.43 801.00 401.22 (M+2H)²+ ESI+
12 Argireline 884.46 888.07 443.23 (M+2H)²+ ESI+
13 Matrixyl 1063.66 1064.36 532.83 (M+2H)²+ ESI+
14 SNAP-8 1069.58 1072.28 535.79 (M+2H)²+ ESI+
15 BPC-157 1414.70 1419.58 708.35 (M+2H)²+ ESI+
16 AOD-9604 1810.87 1815.10 906.44 (M+2H)²+ ESI+
17 MOTS-c 2168.20 2174.49 723.73 (M+3H)³+ ESI+
18 Humanin 2682.49 2687.10 895.17 (M+3H)³+ ESI+
19 CJC-1295 3313.90 3315.74 1105.31 (M+3H)³+ ESI+
20 Sermorelin 3354.91 3357.86 1119.31 (M+3H)³+ ESI+
21 Semaglutide 4107.10 4113.60 1027.53 (M+4H)⁴+ ESI+
22 Tirzepatide 4807.54 4813.50 1202.89 (M+4H)⁴+ ESI+
23 Retatrutide 4865.58 4872.50 1217.40 (M+4H)⁴+ ESI+
24 TB-500 4957.24 4963.54 1653.42 (M+3H)³+ ESI+

View peptide molecular weights at AMP Peptide