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[Tyr8] Substance P is an 11-residue Substance P analog in which Phe8 is replaced by tyrosine. The remainder of the native sequence, including the amidated C-terminal Met11, is retained.
The added phenolic group at Tyr8 makes this analog especially useful in Substance P labeling and radioligand research while preserving a peptide framework closely related to the native NK1 receptor ligand.
Product Information
| Product Name | [Tyr8] Substance P |
| Catalog No. | AS2576 |
| CAS No. | 55614-10-3 |
| Sequence | Arg-Pro-Lys-Pro-Gln-Gln-Phe-Tyr-Gly-Leu-Met-NH2 |
| One-Letter Sequence | RPKPQQFYGLM |
| Peptide Length | 11 residues |
| Molecular Formula | C63H98N18O14S |
| Molecular Weight | Approximately 1363.6 Da |
| Key Substitution | Phe8 → Tyr |
| C-Terminus | Amidated |
| Research Use | NK1 ligand and radioligand research analog |
| Purity Options | Crude to 98% |
Phe8 to Tyr Substitution
Phe and Tyr share an aromatic side-chain framework, but Tyr contains an additional phenolic hydroxyl group. This creates a chemically addressable aromatic residue at position 8 without making a large change in side-chain size.
The modification has made [Tyr8]-Substance P useful as a biologically active Substance P analog and as a precursor or tracer in radioligand studies.
Why Tyr8 Is Useful in Ligand Studies
Tyrosine provides a convenient site for radioiodination chemistry. Historical receptor-binding studies therefore used Tyr-containing Substance P analogs to investigate the distribution and pharmacology of Substance P binding sites.
We recommend distinguishing the activity of the unlabeled parent analog from that of an iodinated derivative. Addition of iodine changes molecular mass and side-chain properties, so binding characteristics should not automatically be assumed to be identical.
Research Applications
[Tyr8] Substance P can support NK1 receptor binding studies, Substance P localization, radioligand development, receptor distribution experiments and structure–activity comparisons involving aromatic residue 8.
Met11 remains present and can undergo oxidation, which should be monitored in experiments requiring high chemical uniformity.
Frequently Asked Questions
What is changed in [Tyr8] Substance P?
Phe8 of native Substance P is replaced by Tyr.
Why is Tyr useful for radioligand studies?
The phenolic aromatic ring of tyrosine provides a useful site for radioiodination chemistry.
Does the peptide still contain Met11?
Yes. The native C-terminal Met-NH2 is retained.
Is [Tyr8] Substance P biologically active?
Yes. It is used as a biologically active Substance P analog in NK1-associated binding and receptor studies.