[D-Pro4,D-Trp7,9,Nle11]-Substance P (4-11) is an eight-residue modified Substance P fragment developed as a peptide tachykinin antagonist.

The analog combines D-Pro4 and D-Trp7,9 stereochemical substitutions with a Met11 → Nle replacement, producing a molecule that differs from native Substance P in both receptor pharmacology and C-terminal oxidation behavior.

Product Information

D-Amino Acids and Nle11 in an SP(4-11) Antagonist

The peptide retains the C-terminal eight-residue length of Substance P while making several coordinated modifications. D-Pro and D-Trp residues alter stereochemistry at positions involved in receptor recognition, while Nle replaces the oxidation-sensitive terminal methionine.

This combination was part of an early strategy for converting C-terminal Substance P fragments from agonist scaffolds into peptide antagonists.

Experimental Interpretation

Classical studies used this peptide to inhibit Substance P-associated responses in smooth-muscle, vascular and neural systems. Historical peptide antagonists can nevertheless display tissue-dependent activity because early tachykinin assays contained heterogeneous receptor populations.

We therefore recommend reporting the tissue, species and agonist used in antagonist experiments rather than describing a single historical potency value as universally applicable to NK1.

Research Applications

The peptide can support NK1 antagonist research, classical tachykinin pharmacology, Substance P SAR and studies of D-amino-acid substitution in peptide antagonists.

The Nle11 substitution also eliminates methionine oxidation at the C-terminal position.

Frequently Asked Questions

Is this a Substance P agonist or antagonist?

It was developed and characterized primarily as a peptide Substance P / NK1 antagonist.

Why is Nle11 included?

Nle provides a hydrophobic C-terminal residue without the sulfur atom responsible for methionine oxidation.

How many D-amino acids are present?

Three: D-Pro4, D-Trp7 and D-Trp9.

Research Use Only.