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[Arg3] Substance P is an 11-residue tachykinin corresponding to the naturally occurring chicken form of Substance P. It differs from mammalian Substance P by a single Lys3-to-Arg substitution while retaining the conserved amidated C-terminal sequence required for tachykinin receptor recognition.
This natural species variant provides a useful system for investigating how a conservative basic-residue substitution influences Substance P pharmacology without extensively redesigning the peptide scaffold.
Product Information
| Property | Specification |
|---|---|
| Product Name | [Arg3] Substance P |
| Sequence | Arg-Pro-Arg-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH₂ |
| One-Letter Sequence | RPRPQQFFGLM-NH₂ |
| Peptide Length | 11 amino-acid residues |
| Molecular Formula | C63H98N20O13S |
| Molecular Weight | Approximately 1375.67 Da |
| Key Difference | Lys3 → Arg relative to mammalian Substance P |
| C-Terminus | Met-NH₂ |
| Research Context | Tachykinin biology, species variation and Substance P SAR |
A Naturally Occurring Substance P Variant
[Arg3] Substance P was identified in chicken small intestine rather than being created solely as an artificial laboratory analog. Its sequence preserves the overall Substance P architecture while replacing the positively charged Lys at position 3 with Arg.
This distinction makes the peptide useful for comparative studies in which receptor-active C-terminal residues remain unchanged while the N-terminal region contains a defined natural substitution.
Preserved Tachykinin Activity
In the original characterization, synthetic [Arg3] Substance P reproduced the chromatographic and immunochemical behavior of the isolated chicken peptide and showed activity comparable with mammalian Substance P in guinea pig ileum contraction experiments.
We recommend treating those observations as assay-specific evidence rather than assuming identical potency in every recombinant NK1 receptor system.
Experimental Considerations
The C-terminal Phe-Phe-Gly-Leu-Met-NH₂ region is retained, preserving a key portion of the tachykinin pharmacophore. The sequence also contains Met11, so methionine oxidation should be considered during storage and LC-MS interpretation.
Related neuroactive peptides can be explored in our Neurotransmitters & Neuropeptides collection.
Frequently Asked Questions
How does [Arg3] Substance P differ from mammalian Substance P?
Arginine replaces lysine at position 3; the remaining sequence is conserved.
Is [Arg3] Substance P an artificial analog?
No. This sequence has been isolated as the native chicken form of Substance P.