- Free UK delivery · same-day dispatch before 3pm
- Independent third-party testing by PeptideVerify
- Shop all research peptides
- Learn: guides and research tools
Peptide reference data
Composition, mass and UV absorption constants for 21 peptides, every figure calculated from the amino acid sequence. Download it as CSV and cite it.
For research use only. Not for human or veterinary use. Sold strictly for in-vitro laboratory research; not for diagnosis or treatment.
| Peptide | Sequence (one-letter) | Formula | Average mass (Da) | Monoisotopic mass (Da) | Trp | Tyr | Cys | ε280 (M⁻¹ cm⁻¹) | ε205 (M⁻¹ cm⁻¹) | Net charge, pH 7 | Calculator |
|---|---|---|---|---|---|---|---|---|---|---|---|
| British Peptide Labs catalogue | |||||||||||
| CagrilintideCAS 1415456-99-3 | HOOC-(CH2)18-CO-γGlu-KCNTATCATQRLAEFLRHSSNNFGPILPPTNVGSNTP-NH2Disulfide Cys2–Cys7 | C194H312N54O59S2 | 4409.01 | 4406.2515 | 0 | 0 | 2 | — | 128,960 | +0.2 | Open |
| BPC-157CAS 137525-51-0 | GEPPPGKPADDAGLV | C62H98N16O22 | 1419.54 | 1418.7042 | 0 | 0 | 0 | — | 38,920 | −2.0 | Open |
| GHK-CuCAS 89030-95-5 | GHK · Cu(II) | C14H22CuN6O4 | 401.91 | 401.0999 | 0 | 0 | 0 | — | — | — | Open |
| MT2CAS 121062-08-6 | Ac-[Nle]DHfRWK-NH2Lactam Asp2–Lys7Lower case = D-residue | C50H69N15O9 | 1024.18 | 1023.5403 | 1 | 0 | 0 | 5,500 | 52,230 | +1.2 | Open |
| IpamorelinCAS 170851-70-4 | [Aib]H[D-2-Nal]fK-NH2Lower case = D-residue | C38H49N9O5 | 711.85 | 711.3857 | 0 | 0 | 0 | — | — | +2.2 | Open |
| MOTS-cCAS 1627580-64-6 | MRWQEMGYIFYPRKLR | C101H152N28O22S2 | 2174.59 | 2173.1077 | 1 | 2 | 0 | 8,480 | 90,970 | +3.0 | Open |
| SS-31CAS 736992-21-5 | r[Dmt]KF-NH2Lower case = D-residue | C32H49N9O5 | 639.79 | 639.3857 | 0 | 0 | 0 | — | — | +3.0 | Open |
| SelankCAS 129954-34-3 | TKPRPGP | C33H57N11O9 | 751.87 | 751.4341 | 0 | 0 | 0 | — | 18,030 | +2.0 | Open |
| SemaxCAS 80714-61-0 | MEHFPGP | C37H51N9O10S | 813.92 | 813.3480 | 0 | 0 | 0 | — | 32,310 | −0.8 | Open |
| Reference peptides | |||||||||||
| Leu-enkephalin | YGGFL | C28H37N5O7 | 555.62 | 555.2693 | 0 | 1 | 0 | 1,490 | 25,800 | 0.0 | Open |
| Met-enkephalin | YGGFM | C27H35N5O7S | 573.66 | 573.2257 | 0 | 1 | 0 | 1,490 | 27,630 | 0.0 | Open |
| Kemptide | LRRASLG | C32H61N13O9 | 771.91 | 771.4715 | 0 | 0 | 0 | — | 19,380 | +2.0 | Open |
| Bradykinin | RPPGFSPFR | C50H73N15O11 | 1060.21 | 1059.5614 | 0 | 0 | 0 | — | 42,140 | +2.0 | Open |
| Angiotensin I (human) | DRVYIHPFHL | C62H89N17O14 | 1296.48 | 1295.6775 | 0 | 1 | 0 | 1,490 | 51,450 | +0.5 | Open |
| Substance P | RPKPQQFFGLM-NH2 | C63H98N18O13S | 1347.63 | 1346.7281 | 0 | 0 | 0 | — | 48,980 | +3.0 | Open |
| GHRP-6 | HwAWfK-NH2Lower case = D-residue | C46H56N12O6 | 873.01 | 872.4446 | 2 | 0 | 0 | 11,000 | 68,500 | +2.2 | Open |
| Neurotensin | [pGlu]LYENKPRRPYIL | C78H121N21O20 | 1672.92 | 1671.9097 | 0 | 2 | 0 | 2,980 | 48,620 | +1.0 | Open |
| Bombesin | [pGlu]QRLGNQWAVGHLM-NH2 | C71H110N24O18S | 1619.85 | 1618.8151 | 1 | 0 | 0 | 5,500 | 66,120 | +1.2 | Open |
| Fibrinopeptide A (human) | ADSGEGDFLAEGGGVR | C63H97N19O26 | 1536.56 | 1535.6852 | 0 | 0 | 0 | — | 51,650 | −3.0 | Open |
| [Glu1]-fibrinopeptide B | EGVNDNEEGFFSAR | C66H95N19O26 | 1570.57 | 1569.6696 | 0 | 0 | 0 | — | 55,490 | −3.0 | Open |
| Melittin | GIGAVLKVLTTGLPALISWIKRKRQQ-NH2 | C131H229N39O31 | 2846.46 | 2844.7542 | 1 | 0 | 0 | 5,500 | 93,400 | +6.0 | Open |
Methods
Every value is calculated in code from the sequence when the page is built; nothing is typed in by hand. The catalogue rows use the sequences on our product pages, and each computed formula matches the one on the product page.
- Molecular formula: the sum of residue formulas plus one water, adjusted for acetyl caps, C-terminal amides, pyroglutamate, side-chain lactams, disulfide bonds (−2 H each) and metal centres. Written in Hill order.
- Average mass: IUPAC 2007 standard atomic weights (C 12.0107, H 1.00794, N 14.0067, O 15.9994, S 32.065, Cu 63.546). Monoisotopic mass: the most abundant isotope of each element (AME 2016).
- ε280 (Pace et al., 1995): 5,500 per Trp, 1,490 per Tyr and 125 per disulfide bond. Given for sequences with at least one Trp or Tyr.
- ε205 (Anthis & Clore, 2013): 2,780 per backbone peptide bond, plus Trp 20,400, Phe 8,600, Tyr 6,080, His 5,200, Met 1,830, Arg 1,350, Cys 690, Gln 400 and Asn 400.
- Both coefficients come from the same functions as our molarity calculator. Aib, Nle and pyroglutamate carry no side-chain chromophore and add nothing to either sum; residues with their own chromophore (Dmt, 2-Nal) and the copper complex are listed by composition and mass.
- Net charge: the Henderson–Hasselbalch sum at pH 7 with the EMBOSS pK set (N-terminus 8.6, C-terminus 3.6, Lys 10.8, Arg 12.5, His 6.5, Asp 3.9, Glu 4.1, Cys 8.5, Tyr 10.1). Capped termini, lactam-bridged side chains and bonded cysteines are not counted.
Reading the sequences
- One-letter codes, N- to C-terminus. Lower case marks a D-residue.
- Residues without a one-letter code appear in brackets: [Aib] α-aminoisobutyric acid, [Nle] norleucine, [Dmt] 2′,6′-dimethyltyrosine, [2-Nal] 3-(2-naphthyl)alanine, [pGlu] pyroglutamic acid.
- Ac- is an N-terminal acetyl group and -NH2 a C-terminal amide; a free acid has no suffix.
- Bridges are listed under the sequence with their residue numbers.
How to cite
British Peptide Labs. Peptide reference data. https://britishpeptidelabs.com/peptide-reference-data, accessed [date].
Free to reuse with attribution under CC BY 4.0. Link to this page, or cite it as above. CC BY 4.0 (opens in a new tab)
References
- 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 (opens in a new tab)
- Anthis NJ, Clore GM. Sequence-specific determination of protein and peptide concentrations by absorbance at 205 nm. Protein Science. 2013;22(6):851–858. doi:10.1002/pro.2253 (opens in a new tab)
- 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 (opens in a new tab)
Frequently asked questions
Add the residue formulas, add one water for the free termini, then adjust for any modification: an acetyl cap adds C2H2O, a C-terminal amide swaps OH for NH2 and each disulfide bond removes two hydrogens. Multiply each element count by its atomic weight and sum.
Average mass weights each element by its natural isotope mix and is the figure for weighing and molarity. Monoisotopic mass uses only the most abundant isotope and matches the first peak of a mass spectrum.
Those with at least one Trp or Tyr. For the rest, ε205 is the coefficient to use, and it is given for every peptide built from residues in the Anthis & Clore set.
Yes. The table and the CSV are free to reuse under CC BY 4.0. Cite the page with the line under How to cite.