VIP

VIP is a 28-residue peptide with the sequence HSDAVFTDNYTRLRKQMAVKKYLNSILN and a C-terminal amide, and it is the founding ligand of the VPAC receptor pair. The amidated native form corresponds to C147H238N44O42S at about 3325.8 g/mol, while PubChem depicts the free acid at C147H237N43O43S and 3326.8 g/mol under CID 53314964 and CAS 37221-79-7. The chain has no cysteine and no disulfide bond. Four lysines, two arginines and one histidine set against two aspartates leave it basic at neutral pH, and the single methionine at position 17 is the residue analysts watch most closely.

VIP belongs to the secretin and glucagon peptide superfamily, the same structural grouping as growth hormone releasing hormone and PACAP, rather than to the short synthetic research peptides. The human and porcine sequences are identical, and the nonproprietary name aviptadil denotes the same chain. Research-grade material is assembled by solid-phase synthesis and supplied as a lyophilized (freeze-dried) solid. Aviptadil, the international nonproprietary name for this sequence, holds no approved indication in the United States, and material carrying that name has been marketed outside the United States only as one component of a combination product. The research-grade peptide listed here is not that product. This entry covers the synthetic research-grade peptide only, and the identity figures above are reconciled against the Certificate of Analysis for the lot in hand. VIP is sold for research use only and is not for human or veterinary use.

VIP entered the literature as a purification product rather than a designed molecule. Said and Mutt reported its isolation from porcine small intestine in 1970 (PubMed 5450698), then published the 28-residue sequence four years later (PubMed 4829446).

The receptor record came two decades later. Ishihara and colleagues cloned and functionally expressed the first VIP receptor in 1992 and mapped its tissue distribution (PubMed 1314625). Lutz and colleagues characterised a second, distinct receptor cDNA in 1993, establishing the pair now named VPAC1 and VPAC2 (PubMed 8224221). Couvineau and colleagues later reviewed VPAC1 as a class B GPCR prototype (PubMed 23162538).

The evidence base is deep at the level of sequence, receptor identity and receptor pharmacology, replicated across independent laboratories. Whole-animal work is more scattered. Nothing here describes an outcome in a person. Every reference below was checked against PubMed retraction records; none carries a retraction notice.

The mechanism reported for VIP is agonism at two class B G protein-coupled receptors, VPAC1 (gene VIPR1) and VPAC2 (gene VIPR2). Class B receptors carry a large extracellular N-terminal domain, and binding follows a two-domain model: the peptide’s C-terminal half docks into that domain, positioning its N-terminus to engage the transmembrane bundle. In transfected cells the activated receptors couple mainly to Gs, raising adenylate cyclase activity and cyclic AMP (PubMed 23162538).

Two distinctions are useful. VIP does not discriminate strongly between VPAC1 and VPAC2, so separating the two calls for receptor-selective analogues rather than VIP alone. VIP also shares those receptors with PACAP, but the family’s third receptor, PAC1, is PACAP-preferring and responds far more weakly to VIP. Confusing the three is the commonest error here.

A methodology caveat applies. Most quantitative pharmacology comes from transfected lines expressing one cloned receptor at non-native density, and peptidases degrade the peptide quickly in tissue preparations, so reported potencies belong to the assay.

Sealed lyophilized VIP is stored at -20°C, shielded from light, in the unopened container. No duration is asserted here: the stability window is on the batch Certificate of Analysis.

Lyophilized peptide is hygroscopic, meaning it takes up atmospheric moisture, so a container reaches ambient temperature before opening. Freeze-thaw cycling is avoided. Methionine 17 is the oxidation-sensitive residue, the reason to keep the container dark as well as cold.

Reconstitution is the term for returning a lyophilized compound to solution; this page defines it and gives no procedure. VIP carries a net positive charge from its lysine, arginine and histidine content and sits in the aqueous solubility class.

Solid material is handled in low humidity with minimal open-container exposure. Basic peptides adsorb to glass and plastic, shifting effective concentration in dilute samples. Preparation parameters belong to the cited methodology and the lot COA.

Identity and purity here are established by reverse-phase high-performance liquid chromatography and mass spectrometry, the primary check being a mass consistent with 3325.8 g/mol. Verified purity is documented per lot on the COA.

Three checks are specific here. The C-terminal amide is confirmed rather than assumed, since a free acid lot differs by about one mass unit and is a different molecule for receptor work. Methionine oxidation adds 16 mass units and resolves as a separate peak. Deletion sequences accumulate across a 28-residue synthesis, and counter-ion content sets fill weight against peptide.

VIP is catalogued with peptides studied in defined receptor systems.

• Sermorelin.
  A GHRH(1-29) analogue from the same superfamily, at a separate class B receptor.
• Tesamorelin.
  A further GHRH-receptor analogue, useful as a specificity control.
• Thymosin Alpha-1.
  Another 28-residue peptide studied in immune-signalling models.
• Oxytocin.
  A neuropeptide at a class A GPCR, a contrast in architecture.

Said SI, Mutt V (1970). Polypeptide with broad biological activity: isolation from small intestine. Science.
PubMed 5450698

Mutt V, Said SI (1974). Structure of the porcine vasoactive intestinal octacosapeptide. The amino-acid sequence. Eur J Biochem.
PubMed 4829446

Ishihara T, Shigemoto R, Mori K, et al. (1992). Functional expression and tissue distribution of a novel receptor for vasoactive intestinal polypeptide. Neuron.
PubMed 1314625

Lutz EM, Sheward WJ, West KM, et al. (1993). The VIP2 receptor: molecular characterisation of a cDNA encoding a novel receptor for vasoactive intestinal peptide. FEBS Lett.
PubMed 8224221

Couvineau A, Ceraudo E, Tan YV, et al. (2012). The VPAC1 receptor: structure and function of a class B GPCR prototype. Front Endocrinol (Lausanne).
PubMed 23162538

Peptides.com lists one VIP research product, a sealed lyophilized vial from Real Peptides at a 5mg fill. That per-vial strength is a product specification, not a research quantity. Vials are the only listed format. VIP is new to the catalogue with no chemical information page, so the identity figures come from PubChem. Each lot ships with a published COA.

• Browse all VIP research products

• Real Peptides VIP, 5mg lyophilized vial

These products are sold for Research Use Only and are not intended for human consumption.