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Substance P (6-11), also known as Hexa Substance P, is the C-terminal hexapeptide Gln-Phe-Phe-Gly-Leu-Met-NH2. The fragment retains the amidated hydrophobic C-terminal pharmacophore of native Substance P and remains biologically active at the NK1 receptor.
Removal of residues 1–5 substantially reduces potency relative to full-length Substance P while preserving receptor-activating capacity. This makes SP(6-11) useful for defining the minimum structural requirements for NK1 activation, comparing N-terminal contributions to signaling, and studying C-terminal Substance P metabolism.
Product Information
| Product Name | Substance P (6-11) |
| Catalog No. | AS2732 |
| CAS No. | 51165-07-2 |
| Synonym | Hexa Substance P |
| Sequence | Gln-Phe-Phe-Gly-Leu-Met-NH2 |
| One-Letter Sequence | QFFGLM-NH2 |
| Peptide Length | 6 residues |
| Molecular Formula | C36H52N8O7S |
| Molecular Weight | Approximately 740.9 Da |
| C-Terminus | Amidated |
| Pharmacological Profile | NK1 receptor agonist fragment |
C-Terminal Substance P Pharmacophore
The Phe-Phe-Gly-Leu-Met-NH2 region contains major structural determinants for tachykinin receptor recognition. SP(6-11) retains this region while removing the basic and polar N-terminal portion of full-length Substance P.
Curated human NK1 receptor data classify SP(6-11) as a full agonist, with reported pIC50 values of approximately 6.3–6.5. Its lower potency relative to native Substance P demonstrates that the C-terminal sequence can activate NK1, while upstream residues substantially improve receptor interaction.
Why Compare SP(6-11) with Full-Length Substance P?
The comparison helps separate core receptor activation from contributions made by the N-terminal sequence to potency, receptor engagement and downstream signaling.
We recommend using both peptides when the experimental question concerns the minimum NK1-active pharmacophore rather than treating SP(6-11) as an interchangeable substitute for full-length Substance P.
Research Applications
Substance P (6-11) can support NK1 receptor pharmacology, C-terminal tachykinin SAR, peptide metabolism studies and comparative signaling experiments involving full-length and truncated Substance P.
Frequently Asked Questions
Is Substance P (6-11) biologically active?
Yes. It retains NK1 receptor agonist activity, although it is less potent than full-length Substance P.
Is SP(6-11) the same as Septide?
No. Septide contains additional pyroglutamate and Pro9 modifications.
Is the C-terminus amidated?
Yes. The sequence terminates in Met-NH2.