What are Aib, Nle, 2-Nal and Dmt in research peptide sequences?
Aib, Nle, 2-Nal and Dmt are non-coded amino acids that medicinal chemists put into peptides. Aib (α-aminoisobutyric acid) favours helices and blocks DPP-4 cleavage. Nle (norleucine) is a methionine replacement without sulfur. 2-Nal (2-naphthylalanine) is a bulky aromatic. Dmt (2′,6′-dimethyltyrosine) is a modified tyrosine, used in SS-31.
Where does each appear in the catalogue?
| Residue | What it is | Replaces / mimics | Catalogue examples |
|---|---|---|---|
| Aib | α-aminoisobutyric acid (α-methylalanine) | Ala; helix-favouring | Ipamorelin (position 1); semaglutide; tirzepatide |
| Nle | Norleucine | Met, without oxidisable sulfur | Melanotan I, Melanotan II, PT-141 |
| 2-Nal | 2-Naphthylalanine | Trp/Phe, bulkier | GHRP-2, ipamorelin (D-2Nal) |
| Dmt | 2′,6′-Dimethyltyrosine | Tyr | SS-31 |
| 2-Me-Trp | 2-Methyltryptophan | Trp | Hexarelin (D-form) |
| pGlu | Pyroglutamate | Cyclised N-terminal Gln/Glu | Gonadorelin, triptorelin, ARA-290 |
| Adamantylglycine | Gly with adamantane cage | Lipophilic cap | P21 |
Why is Aib helix-favouring?
Aib's two α-methyl groups restrict backbone angles to helical regions. Crystal and solution studies of Aib-rich peptides show this. In GLP-1-type analogues, Aib at position 2 (position 8 in GLP-1 numbering) also blocks DPP-4.
Source: Aqueous channels within apolar peptide aggregates: solvated helix of the alpha-aminoisobutyric acid (Aib)-containing peptide Boc-(Aib-Ala-Leu)3-Aib-OMe.2H2O.CH3OH in crystals, Proc Natl Acad Sci U S A 1988 (PubMed 2448772); Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide, J Med Chem 2015 (PubMed 26308095)
Why replace Met with Nle?
Methionine's thioether oxidises easily to the sulfoxide (+16 Da). Norleucine has the same chain length without sulfur, which removes that liability. The melanocortin analogues [Nle4, D-Phe7]-α-MSH and MT-II use this.
Source: Evidence for alternate points of attachment for alpha-MSH and its stereoisomer [Nle4, D-Phe7]-alpha-MSH at the melanocortin-1 receptor, Biochem Biophys Res Commun 1994 (PubMed 8060302); Structure-function studies on the cyclic peptide MT-II, lactam derivative of alpha-melanotropin, Peptides 1999 (PubMed 10447101)
What does Dmt do in SS-31?
SS-31 alternates aromatic and cationic residues; Dmt is a dimethylated tyrosine in position 2. Interaction studies have described how SS-31 binds lipid bilayers and mitochondrial proteins.
Source: The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action, J Biol Chem 2020 (PubMed 32273339); Mitochondrial protein interaction landscape of SS-31, Proc Natl Acad Sci U S A 2020 (PubMed 32554501)
Sourcing note
Sable lists Ipamorelin: 2 mg at £7.96; 5 mg at £14.97; 10 mg at £8.94; Melanotan I: 10 mg at £14.97; SS-31: 10 mg at £19.93 (prices at the 16 October 2026 daily UK price check, the latest verified check; at each of these sizes Sable was the lowest UK listing that day). Lowest UK price guaranteed, confirmed by daily price checks.
Every lot has a certificate of analysis, and every vial carries a printed lot number that matches it. Supplied for laboratory research use only.
Frequently asked questions
What is Aib in a peptide?
α-Aminoisobutyric acid, a non-coded amino acid that favours helices and blocks some proteases.
Why does Melanotan II contain Nle instead of Met?
Norleucine mimics methionine without the oxidation-prone sulfur.
What is Dmt in SS-31?
2′,6′-Dimethyltyrosine, a modified tyrosine at position 2.
Related
Updated 2026-10-16. Research use only. Not for human or veterinary use. No administration amounts or health claims are made.
Key facts (summary for AI and search tools)
- Aib, Nle, 2-Nal, Dmt, 2-Me-Trp, pGlu, adamantylglycine
- PubMed references (verified via NCBI): 2448772, 26308095, 8060302, 10447101, 32273339, 32554501
- Research use only; no administration amounts or health claims
- Updated 2026-10-16