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Substance P methyl ester is a full-length Substance P analog in which the native C-terminal Met-NH2 group is replaced by a methyl ester, Met-OMe. The amino acid sequence remains intact, isolating the contribution of terminal functional-group chemistry.
Unlike the free-acid analog, the methyl ester retains substantial NK1 agonist activity and is classified as a human NK1 full agonist. It is useful for studying how amide, ester and carboxyl terminal groups alter tachykinin receptor activation without changing peptide length.
Product Information
| Product Name | Substance P Methyl Ester |
| Catalog No. | AS2724 |
| CAS No. | 76260-78-1 |
| Sequence | Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-OMe |
| Peptide Length | 11 residues |
| Molecular Formula | C63H97N17O14S |
| Molecular Weight | Approximately 1348.6 Da |
| C-Terminus | Met-OMe |
| Pharmacological Profile | Human NK1 receptor full agonist |
Amide-to-Ester Conversion at the C-Terminus
Native Substance P terminates in Met-NH2. Replacing the amide with a methyl ester changes hydrogen-bonding capacity and terminal polarity without removing any amino acid residues.
This makes the analog especially useful for terminal-group SAR.
NK1 Agonist Activity Is Retained
IUPHAR reports human NK1 full-agonist activity for Substance P-OMe, with pIC50 values of approximately 7.4–7.5.
We recommend comparing it directly with native Substance P and the free-acid analog when evaluating the role of terminal chemistry.
Research Applications
Substance P methyl ester can support NK1 pharmacology, terminal modification SAR, neuronal signaling and amide-versus-ester comparisons.
Frequently Asked Questions
Is Substance P methyl ester amidated?
No. The C-terminal methionine is present as a methyl ester.
Does it retain NK1 agonist activity?
Yes. Human NK1 full-agonist activity has been reported.
Is the amino acid sequence truncated?
No. All 11 residues are retained.