Other · Conformationally constrained opioid tetrapeptide
TIPP
Also known as Tyr-Tic-Phe-Phe
A Tic-containing tetrapeptide used to investigate δ-opioid receptor binding, antagonism and conformational selectivity.
- Length
- 4 amino acid residues, including non-proteinogenic Tic
- Half-life
- Not well characterised
- Mechanism
- TIPP binds preferentially to the δ-opioid receptor (DOP; OPRD1) and is principally characterised as an antagonist. Its constrained Tic residue helps establish the opioid-binding conformation, while activity at other opioid receptors should be assessed separately.
- Studied in
- Receptor-binding assays, recombinant opioid-receptor signalling systems and isolated tissue preparations use TIPP to investigate δ-opioid receptor pharmacology.
About TIPP
TIPP is a synthetic opioid tetrapeptide with the sequence Tyr-Tic-Phe-Phe, where Tic denotes L-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid. It emerged from structure–activity studies of constrained opioid peptides in the early 1990s. Unlike a naturally processed neuropeptide, its backbone was deliberately designed to restrict conformational freedom. The N-terminal tyrosine contributes a familiar opioid recognition element, while Tic at position two strongly influences receptor selectivity and intrinsic activity.
Its principal experimental target is the δ-opioid receptor, a Gi/o-coupled receptor encoded by OPRD1. TIPP is commonly used as an antagonist in competition-binding and functional assays, including studies of agonist-dependent inhibition of cyclic AMP. Isolated tissue experiments provide an additional functional context for antagonist characterisation. Comparisons with related Tic-containing peptides help distinguish binding affinity from efficacy, since small backbone or terminal changes can alter the pharmacological profile substantially.
Laboratory notes
- Confirm the free-acid sequence and Tic stereochemistry on the analytical certificate; terminal modifications can alter opioid-receptor pharmacology.
- Use low-binding labware and verify the recovered concentration when preparing dilute assay solutions.
- Pair competition-binding data with a functional antagonist assay and counterscreen μ- and κ-opioid receptors.
Storage and reconstitution basics: storage guide.
Questions about TIPP
What does Tic represent in the sequence?
Tic is tetrahydroisoquinoline-3-carboxylic acid, a conformationally restricted, non-proteinogenic amino acid. The standard TIPP structure contains the L-configured residue.
Is TIPP identical to TIPP-psi?
No. TIPP retains the conventional peptide bond between Tic and the adjacent phenylalanine; TIPP-psi replaces that bond with a reduced amide linkage.
Does receptor binding alone establish antagonism?
No. Binding establishes affinity, whereas antagonism requires functional testing against an agonist response in a defined receptor system.
Is TIPP for human use?
No. It is supplied strictly for in-vitro laboratory research and is not for human or animal consumption.
Related research peptides
All products are sold for laboratory research use only. Not for human consumption, not a medicine, not for diagnosing, treating or preventing any condition.