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Substance P (7-11) is the C-terminal pentapeptide Phe-Phe-Gly-Leu-Met-NH2 of Substance P.
The fragment preserves the hydrophobic aromatic C-terminal region shared by the native neuropeptide while removing residues 1-6, making it useful for defining the minimum sequence requirements for tachykinin receptor recognition.
Product Information
| Product Name | Substance P (7-11) |
| CAS No. | 51165-05-0 |
| Sequence | Phe-Phe-Gly-Leu-Met-NH2 |
| One-Letter Sequence | FFGLM-NH2 |
| Peptide Length | 5 residues |
| Molecular Formula | C31H44N6O5S |
| Molecular Weight | Approximately 612.8 Da |
| C-Terminus | Met-NH2 |
The Hydrophobic C-Terminal Pentapeptide Is Not NK1-Selective
Studies using cloned rat NK1, NK2 and NK3 receptors found that SP(7-11) bound all three receptor subtypes with broadly similar micromolar affinity, approximately 2–20 μM depending on the receptor.
This result shows that the hydrophobic C-terminal pentapeptide contains general tachykinin receptor-recognition information but lacks the N-terminal interactions that give full-length Substance P its stronger NK1 preference.
We consider this a particularly useful control when studying how additional N-terminal residues improve receptor subtype selectivity.
Fragment Length Changes Pharmacology
Adding residues upstream of SP(7-11) progressively changes affinity and receptor discrimination. The Pro-Gln-Gln region in longer Substance P fragments is particularly important for optimizing interaction with NK1.
This makes SP(7-11) more informative as a minimal pharmacophore and SAR fragment than as a direct substitute for full-length Substance P.
Research Applications
Substance P (7-11) can support tachykinin fragment SAR, minimal pharmacophore studies, NK1/NK2/NK3 receptor comparisons and peptide metabolism research.
For an even shorter metabolic fragment, Substance P (9-11) provides the terminal Gly-Leu-Met-NH2 sequence.
Frequently Asked Questions
Is SP(7-11) selective for NK1?
No. Cloned rat receptor studies found similar micromolar affinity for NK1, NK2 and NK3.
What affinity range has been reported?
Approximately 2–20 μM across the three cloned rat tachykinin receptors in one comparative study.
Why is the fragment useful if it is not highly selective?
It helps define which parts of the Substance P sequence provide basic receptor recognition and which additional residues generate NK1 selectivity.