Description

VIP (Vasoactive Intestinal Peptide) Research Peptide – 5mg

Peptide Minds offers a high-purity Vasoactive Intestinal Peptide (VIP) research compound, supplied as a lyophilized powder in a sealed 3mL glass vial containing 5mg of active peptide. This product is manufactured exclusively for controlled laboratory research applications and is not intended for human consumption, clinical use, or veterinary purposes.

Molecular Profile

VIP is a 28-residue, C-terminally amidated neuropeptide belonging to the glucagon/secretin superfamily of regulatory peptides. Its primary sequence (HSDAVFTDNYTRLRKQMAVKKYLNSILN-NH2) is fully conserved across human, porcine, and rat species, reflecting a high degree of evolutionary conservation. The peptide has a molecular weight of 3326.82 g/mol and the molecular formula C147H237N43O43S. The single methionine residue at position 17 contains the sole sulfur atom in the molecule. Structural modeling studies predicted a central alpha-helical domain spanning approximately Val-5 through Asn-24, flanked by random-coil conformations at the N- and C-termini. Both the N-terminal and C-terminal regions of the peptide have been demonstrated to contribute to receptor binding activity in alanine-scanning mutagenesis studies.

Laboratory Research Applications

In laboratory settings, VIP has been utilized as a research reagent in multiple experimental contexts. Published studies employed this peptide in cell-based assays examining G protein-coupled receptor (GPCR) activation through its two primary receptors, VPAC1 and VPAC2, both members of the class B (secretin) receptor family. In vitro studies using transfected cell lines, intestinal epithelial cell preparations, murine bone marrow-derived dendritic cells, and peripheral blood mononuclear cell cultures documented VIP-mediated increases in intracellular cyclic AMP (cAMP) accumulation, adenylyl cyclase activation, and phospholipase C signaling as measured by radioligand binding assays, enzyme immunoassay, and Western blot analysis. Animal model investigations examined VIP in the context of gastrointestinal motility, smooth muscle relaxation, circadian rhythm signaling in suprachiasmatic nucleus preparations, and cytokine network profiling under controlled experimental conditions.

Intended Use

This product is sold strictly for in vitro laboratory research and development purposes. It is NOT intended for human or veterinary use, nor for any applications as a drug, food additive, cosmetic, or household chemical. The purchaser assumes full responsibility for use in compliance with all applicable federal, state, and local regulations, and warrants that the compound will be used only for in vitro research purposes.

Handling and Storage

Store lyophilized VIP at -20C in its original sealed container, protected from light, heat, and moisture. Under these conditions, the peptide maintains stability for up to 24 months. Once reconstituted with an appropriate sterile solvent (e.g., bacteriostatic water), the solution should be stored at 2-8C and used promptly. For extended storage, aliquot reconstituted material and return to -20C. Avoid repeated freeze-thaw cycles to preserve peptide integrity. Use aseptic technique during handling to maintain a non-contaminated sterile product.

Quality Assurance

Each batch of VIP from Peptide Minds undergoes rigorous quality control. Identity and purity are confirmed through reverse-phase HPLC analysis (>99% purity), with additional verification via mass spectrometry. A Certificate of Analysis (COA) documenting batch-specific analytical data is provided with every order.

Section 4: Research Background

Discovery & Historical Context

Vasoactive Intestinal Peptide holds a foundational position in the history of neuropeptide and gastrointestinal research. In 1970, Sami Said and Viktor Mutt first isolated a polypeptide with potent vasodilatory properties from porcine small intestinal extracts, publishing their findings in Science (Said and Mutt, 1970). The peptide was named for its initial characterization as a vasoactive factor derived from intestinal tissue.

Subsequent work by Said and Rosenberg (1976) established VIP as a neuropeptide with widespread distribution in both the central and peripheral nervous systems, fundamentally expanding its classification beyond a simple gut hormone. The complete 28-amino-acid sequence was determined and the peptide was recognized as a member of the glucagon/secretin superfamily, sharing structural homology with secretin, glucagon, pituitary adenylate cyclase-activating polypeptide (PACAP), growth hormone-releasing hormone (GHRH), and glucagon-like peptides (GLPs).

The VIP gene was subsequently mapped to human chromosome 6q25.2. Receptor identification followed in the 1990s, with Ishihara and colleagues first cloning a VIP-specific receptor from rat lung tissue in 1991 (later designated VPAC1), followed by identification of the VPAC2 receptor from a rat olfactory bulb cDNA library (Lutz et al., 1993). Both receptors were confirmed in human tissues using cDNA libraries from jejunal epithelial cells expressed in COS-7 cell systems.

Structural Characteristics

VIP is a linear 28-amino-acid peptide with a C-terminal amide group (-NH2) that is essential for full biological activity. The peptide contains no disulfide bonds or post-translational modifications beyond the C-terminal amidation and the naturally occurring N-terminal histidine. The amino acid sequence is identical across human, porcine, and rat species, reflecting high evolutionary conservation.

Three-dimensional structural modeling using ab initio molecular approaches predicted a central alpha-helical domain spanning residues Val-5 through Asn-24, with the N-terminal five residues and C-terminal four residues adopting random-coil conformations. Systematic alanine-scanning mutagenesis studies identified 14 out of 28 positions where substitution produced greater than 10-fold reductions in receptor binding affinity (Ki) or cAMP stimulation potency (EC50). Residues His-1, Val-5, Arg-14, Lys-15, Lys-21, Leu-23, and Ile-26 were identified as critical for biological activity without affecting predicted secondary structure, indicating direct involvement in receptor contact interfaces.

VIP shares approximately 68% amino acid sequence identity with PACAP-27, another member of the secretin superfamily. This structural homology underlies the ability of both peptides to bind VPAC1 and VPAC2 receptors with comparable affinities, while PAC1 receptors show preferential binding to PACAP over VIP.

Receptor Systems Investigated in Research

Laboratory investigations have characterized VIP interactions with two primary G protein-coupled receptors: VPAC1 (VIPR1) and VPAC2 (VIPR2), both belonging to the class B (secretin) GPCR family. These receptors exhibit differential tissue distribution patterns that have been mapped using immunohistochemistry and mRNA expression profiling.

VPAC1 receptor expression was documented broadly across gut epithelium, lung parenchyma, liver, and immune cell populations including monocytes and neutrophils. VPAC2 receptor expression was characterized as more selectively distributed in brain regions (suprachiasmatic nucleus, thalamus, hypothalamus), pancreatic islets, and smooth muscle tissues. The VPAC1 and VPAC2 genes are located on chromosomes 3p22 and 7q36.3, respectively.

Both VPAC1 and VPAC2 are coupled primarily to the stimulatory G protein (Gs), and receptor activation by VIP increases intracellular cAMP through adenylyl cyclase stimulation. This canonical signaling cascade activates protein kinase A (PKA), leading to phosphorylation of CREB transcription factor and regulation of downstream gene expression programs including Per1 and Per2 circadian clock genes. Additional signaling pathways documented in VIP-treated cell systems include phospholipase C (PLC), phospholipase D (PLD), p38 MAPK, MEK1/ERK, and beta-arrestin recruitment pathways.

Receptor activity-modifying protein (RAMP) interactions were also documented. VPAC1 was shown to interact with RAMP2, enhancing inositol trisphosphate production and calcium signaling without affecting cAMP coupling, as demonstrated in CHO cell overexpression systems. VPAC1 was also observed to form homodimers and heterodimers with VPAC2 and secretin receptors.

Laboratory Methodologies

Research protocols employing VIP have utilized a range of standardized laboratory methodologies, including:

• Receptor Binding Assays: 125I-VIP radioligand displacement studies in membrane preparations from cell clones stably expressing human recombinant VPAC1 or VPAC2 receptors, measuring inhibition constants (Ki) and adenylyl cyclase stimulation potency (EC50).
• Cell Culture Assays: In vitro studies using COS-7 cells, CHO cells, HT-29 colonic adenocarcinoma cells, murine bone marrow-derived dendritic cells (BMDCs), human monocyte-derived dendritic cells (MDDCs), and intestinal organoid models to assess cAMP accumulation, cytokine secretion profiles, and cellular differentiation endpoints.
• Animal Model Studies: In vivo investigations in VIP knockout mice, colitis models (TNBS-induced), experimental autoimmune encephalomyelitis (EAE), and sepsis paradigms measuring gastrointestinal motility, smooth muscle contractility, and cytokine network changes.
• Circadian Rhythm Research: Electrophysiological recordings and bioluminescent reporter assays in suprachiasmatic nucleus (SCN) slice preparations examining VIP-mediated neuronal synchronization and Per1/Per2 gene expression dynamics.
• Immunomodulation Studies: Flow cytometric analysis of T-cell polarization (Th1/Th2 balance), dendritic cell maturation markers (CD80, CD86, MHC class II), and intracellular cytokine staining panels in VIP-treated immune cell preparations.
• Analytical Characterization: Reverse-phase HPLC on C18 columns, mass spectrometry (ESI-MS), and NMR spectroscopy for peptide identity confirmation, purity assessment, and structural analysis.

Analytical Characterization

Peptide identity verification employs multiple orthogonal analytical approaches. Reverse-phase HPLC with UV detection at 214nm and 220nm establishes purity and retention time profiles. Electrospray ionization mass spectrometry (ESI-MS) confirms the expected molecular mass of 3326.82 Da and verifies the C-terminal amidation. The methionine residue at position 17 is a known oxidation-sensitive site; analytical protocols should assess methionine sulfoxide formation as a quality indicator, particularly in reconstituted or aged preparations.

Peer-Reviewed References

1. Said SI, Mutt V. Polypeptide with broad biological activity: isolation from small intestine. Science. 1970;169(3951):1217-1218.
2. Said SI, Rosenberg RN. Vasoactive intestinal polypeptide: abundant immunoreactivity in neural cell lines and normal nervous tissue. Science. 1976;192(4236):907-908.
3. Delgado M, Ganea D. Vasoactive intestinal peptide: a neuropeptide with pleiotropic immune functions. Amino Acids. 2013;45(1):25-39.
4. Langer I. Mechanisms involved in VPAC receptors activation and regulation: lessons from pharmacological and mutagenesis studies. Front Endocrinol. 2012;3:129.
5. Nicole P, et al. Identification of key residues for interaction of vasoactive intestinal peptide with human VPAC1 and VPAC2 receptors. J Biol Chem. 2000;275(31):24003-24012.
6. Harmar AJ, et al. Pharmacology and functions of receptors for vasoactive intestinal peptide and pituitary adenylate cyclase-activating polypeptide: IUPHAR review 1. Br J Pharmacol. 2012;166(1):4-17.

Section 5: Regulatory & Compliance Statement

FOR RESEARCH USE ONLY NOT FOR HUMAN CONSUMPTION OR VETERINARY USE This product is sold exclusively for laboratory research applications. It is not approved by the U.S. Food and Drug Administration (FDA) for human use, clinical applications, or therapeutic purposes. VIP (Vasoactive Intestinal Peptide) is FOR RESEARCH USE ONLY. It is not intended for human or veterinary use. This product has not been evaluated by the FDA. Misuse of this product is strictly prohibited and may violate federal, state, or local laws. By purchasing this product, buyer represents and warrants that it will be used only for in vitro research purposes. Peptide Minds (Accelairate LLC) is a chemical supplier. Peptide Minds is not a compounding pharmacy or chemical compounding facility as defined under Section 503A of the Federal Food, Drug, and Cosmetic Act, and is not an outsourcing facility as defined under Section 503B of the same Act. By purchasing from Peptide Minds, the buyer agrees that all products will be used in accordance with applicable laws and regulations, and assumes full responsibility for their use in appropriate research settings only. All technical and descriptive information on this website is provided for research, educational, and informational purposes only. The products and any statements made about them have not been evaluated by the U.S. Food and Drug Administration. The products are not intended to diagnose, treat, cure, or prevent any disease or medical condition.