VIP · Research brief

Buy VIP Peptide — Research-Grade Vasoactive Peptide

Real Peptides Research TeamEditorial

Updated September 24, 20269 min read

60 WORDS

Short answer

VIP is a 28-amino-acid peptide, and two of its residues explain most of the disappointment laboratories report after a shipment lands. Methionine at position 17 oxidises. The asparagine residues deamidate. Neither event changes how the lyophilised powder looks in the vial, and neither one is captured by a certificate of analysis generated on the day of synthesis rather than the…

Key takeaways

VIP is a 28-amino-acid, C-terminally amidated peptide, CAS 37221-79-7, with an average molecular weight near 3,326 Da and an identical sequence across human, porcine and rat.
VIP signals through the VPAC1 and VPAC2 class B G-protein-coupled receptors, activating adenylate cyclase and raising intracellular cyclic AMP.
HPLC purity and net peptide content are different measurements, and a vial can show high purity while containing substantially less peptide by weight due to counterion salt and residual water.
The two degradation routes that matter for stored VIP are methionine-17 oxidation, a roughly 16 Da mass shift, and asparagine deamidation, about 1 Da.
Laboratories that buy VIP peptide should insist on a lot-matched, publicly verifiable certificate of analysis rather than a generic catalogue document.
Research reports a native VIP plasma half-life on the order of minutes, which is why much of the published pharmacology uses stabilised analogs instead.

That gap between synthesis-day data and arrival-day reality is where sourcing decisions quietly go wrong. Our team works in small-batch synthesis with exact amino-acid sequencing, and in supplying Vasoactive Intestinal Peptide to research groups, the same three questions surface every time: is the sequence correct, does the mass confirm it, and what fraction of the vial is actually peptide?

Where can you buy VIP peptide for laboratory research?

You can buy VIP peptide, Vasoactive Intestinal Peptide, CAS 37221-79-7, from research-chemistry suppliers that publish batch-linked, third-party certificates of analysis. Real Peptides supplies VIP as a lyophilised 28-residue peptide for laboratory research use only. Confirm sequence, CAS number and mass spectrometry data against the lot certificate before a purchase order is issued.

Purity percentage is the number everyone fixates on, and it is the one most likely to mislead. A vial listed at 98% HPLC purity can still be well under 98% peptide by weight, because lyophilised material carries counterion salt and residual water that the chromatogram doesn't measure. When you buy VIP peptide, the three figures worth reading together are HPLC purity, net peptide content and the confirmed molecular mass. What follows covers the receptor biology the literature describes, the two degradation routes that ruin correctly synthesised material in storage, and the documentation that separates a verifiable supplier from a listing.

What VIP is, and what the published literature reports

Vasoactive Intestinal Peptide is a 28-amino-acid, C-terminally amidated peptide first isolated from porcine intestinal tissue by Said and Mutt in 1970. It sits in the secretin-glucagon superfamily, and the human, porcine and rat sequences are identical: HSDAVFTDNYTRLRKQMAVKKYLNSILN. Catalogued under CAS 37221-79-7, it has the molecular formula C147H237N43O43S and an average molecular weight near 3,326 Da. Those two identifiers are the first thing to match against a supplier listing, because a mismatched CAS number usually signals a fragment or an analog rather than native VIP.

Mechanistically, VIP is a ligand for VPAC1 and VPAC2, two class B G-protein-coupled receptors, with lower affinity for the PAC1 receptor. Binding drives Gs-protein coupling, which activates adenylate cyclase, raises intracellular cyclic AMP and switches on protein kinase A. That single cAMP-PKA axis is why VIP shows up across such different literatures: smooth muscle relaxation and vasodilation models, immunological work on macrophage cytokine signalling and regulatory T cell populations, and circadian neuroscience, where VIP-expressing neurons of the suprachiasmatic nucleus are described as central to network synchronisation.

One practical consequence matters to anyone designing a study. Research reports a plasma half-life for native VIP on the order of minutes, driven by rapid peptidase cleavage, which is why much of the pharmacology literature works with stabilised analogs or delivery strategies rather than the native sequence. Researchers who buy VIP peptide for receptor-binding or signalling assays are typically working in controlled in vitro systems where that half-life is not the limiting variable.

Two degradation routes a synthesis-day certificate will never show

Correctly synthesised VIP can still fail in your hands, and the two most common chemical routes are predictable from the sequence itself. Methionine at position 17 oxidises to methionine sulfoxide, adding roughly 16 Da to the molecular mass. The asparagine residues undergo deamidation to aspartate and isoaspartate, a pH- and temperature-dependent reaction that adds about 1 Da and is accelerated in neutral-to-alkaline aqueous solution. Both products are detectable by mass spectrometry. Neither is visible to the eye.

This is the part most guides skip. The certificate on a vial documents the batch at the moment of release, not the molecule that arrives at your bench. A lyophilised, desiccated peptide held at minus 20 degrees Celsius, protected from light and moisture, is chemically sluggish. In solution, it is not. The most frequent failure our team sees isn't a defective batch, it's a vial that sat in a warm receiving area over a long weekend, then went into an assay against a certificate describing material that no longer exists in that form.

The defensible workflow is boring and effective: record the arrival temperature, keep the desiccated powder frozen, aliquot to avoid repeated freeze-thaw cycles, and treat any 16 Da mass shift in your own QC as an oxidation flag rather than an instrument artefact. Laboratories that buy VIP peptide in larger lots and run a confirmatory mass check on receipt catch problems before those problems become irreproducible data. All material discussed here is supplied for laboratory research use only, is not an FDA-approved drug, and is not for human or veterinary consumption.

What to verify before you buy VIP peptide

Five documents settle whether a supplier is credible, and none of them are marketing copy. Ask for a lot-matched certificate of analysis showing an HPLC chromatogram with retention time, a mass spectrometry trace confirming a mass consistent with roughly 3,326 Da, a stated net peptide content, the counterion form such as trifluoroacetate or acetate, and the water content. A certificate that reports purity but omits net peptide content is telling you about chromatographic area, not about how much VIP is in the vial.

Lot traceability is the second filter. A generic certificate reused across every batch of a catalogue item is functionally a brochure. The lot number printed on the vial should match the lot number on the document, and the document should be publicly verifiable rather than emailed on request. Our team publishes batch certificates for this reason, because in our experience the single strongest predictor of a reproducible result is whether the buyer could independently confirm what was in the vial six months after the experiment closed.

The third filter is the regulatory statement. Any legitimate research supplier states plainly and in writing that the compound is for laboratory research use only. A supplier that volunteers dosing, preparation or administration guidance alongside a research compound is describing a use it isn't permitted to describe, and that is a reason to walk, not a service.

Comparing the routes for sourcing research-grade VIP

Where you buy VIP peptide determines what documentation you can defend in a methods section. This table compares the four routes labs typically weigh, with the evidence each one produces.

Sourcing route	Documentation typically available	Main identity risk	Bottom line for a research lab
Research-chemistry supplier with batch-linked third-party COAs	HPLC chromatogram, mass spectrometry, net peptide content, lot number, counterion form	Low, provided the certificate is lot-matched rather than generic to the catalogue item	Strongest routine option because the document names the specific batch sitting on your bench
Bulk marketplace listing from an unnamed manufacturer	Often one reused certificate across many lots, sometimes purity only	High, since sequence, salt form and residual water are frequently unstated	Lowest cost per milligram and the hardest position to defend if a reviewer questions identity
Custom synthesis through a contract or academic peptide facility	Full synthesis report, purification data, frequently MS/MS confirmation	Low, though lead times commonly run several weeks	Best fit for labelled, truncated or modified VIP analogs rather than the native 28-mer
Reseller repackaging bulk material	Usually a label and a purity claim with no upstream trace	High, because repackaging breaks the chain of custody from synthesis	Avoid whenever batch traceability is part of your data integrity requirement

What If: VIP Peptide Handling Scenarios

What if the vial arrives at ambient temperature after a shipping delay?

Quarantine the lot and run a confirmatory mass check before it enters any assay. Lyophilised, desiccated VIP tolerates brief ambient exposure far better than material in solution, but tolerance is not the same as verification, and the powder gives you no visual signal either way. Document the arrival condition in your lot record, because an unexplained result three months later is much easier to interpret when the shipping history is written down.

What if the certificate shows 98% HPLC purity but no net peptide content?

Treat the vial mass as an upper bound on peptide mass and request the missing figure before accepting the lot. HPLC purity describes the proportion of peptide-related material in the chromatogram, while net peptide content describes how much of the physical powder is peptide rather than counterion salt and bound water. Skipping this is the most common source of unexplained concentration drift between two supposedly identical batches.

What if the observed mass is 16 Da higher than expected?

Flag it as probable methionine-17 oxidation and re-run before blaming the instrument. That 16 Da addition is the classic signature of methionine converting to methionine sulfoxide, and the literature describes oxidation at this position as capable of altering receptor interaction. If the shift is reproducible across aliquots, the material has degraded rather than been mis-synthesised, and the storage chain is where the investigation should start.

What if a supplier offers dosing or reconstitution instructions with the order?

Read it as a compliance red flag rather than customer service. Real Peptides does not provide dosing, preparation or administration guidance, because these are research-use-only compounds and any such guidance would imply a use they aren't authorised for. What a supplier can legitimately give you is the vial contents in milligrams on the certificate, which is the only input your own concentration framework, expressed as milligrams per millilitre, actually requires.

The blunt truth about research peptide pricing

Here's the honest answer: when the same nominal compound is listed at wildly different prices, the difference is almost never the chemistry. It's the analytics. Third-party mass spectrometry, lot-specific HPLC, net peptide content determination, cold-chain packaging and retained samples all cost money per batch, and a supplier that skips them can undercut one that doesn't while shipping something that may well be correct. May well be. That's the problem. Labs that buy VIP peptide on unit price alone are not buying a cheaper peptide, they're buying an unquantified probability that the vial matches the label, and that probability becomes your reproducibility problem, not the supplier's.

Full batch documentation for our catalogue, including the research-grade VIP listing, is published alongside our certificates of analysis, and the rest of the small-batch peptide catalogue follows the same synthesis and testing standard. Laboratories wanting supply and shipping details can review our facility and service information.

The decision to buy VIP peptide is, in practice, a decision about documentation rather than chemistry. Two vials of correctly synthesised 28-mer VIP are indistinguishable by eye, by solubility and by the number printed on the label. What separates them is whether anyone can prove, eighteen months from now, what was in the one you used. Peptide identity isn't a property of the powder. It's a property of the record that travels with it, and that record is the only part of the purchase you can still check after the experiment is over.

References

Peer-reviewed sources on VIP (Vasoactive Intestinal Peptide) indexed in PubMed, listed for research context. Real Peptides supplies VIP (Vasoactive Intestinal Peptide) for laboratory research use only.

Vasoactive Intestinal Peptide-Secreting Pheochromocytoma: A Case Report and Review of Literature. AACE clinical case reports, 2022. PMID 35959082. doi:10.1016/j.aace.2022.03.003
Vasoactive Intestinal Peptide-Secreting Tumors: A Review. Pancreas, 2019. PMID 31609932. doi:10.1097/MPA.0000000000001402
Neuronal VIP shapes intestinal stem cell activity and mucosal immunity. Cell stem cell, 2026. PMID 41795422. doi:10.1016/j.stem.2026.02.001
Nanoparticle-Driven Tendon Repair: Role of Vasoactive Intestinal Peptide in Immune Modulation and Stem Cell Enhancement. ACS nano, 2025. PMID 40184556. doi:10.1021/acsnano.4c16917
Contribution of Vasoactive Intestinal Peptide to the Depressant Effects of Glucagon-like Peptide-2 on Neurally Induced Contractile Responses in Mouse Ileal Preparations. International journal of molecular sciences, 2025. PMID 41465229. doi:10.3390/ijms262411797
Vasoactive Intestinal Peptide: A Neuropeptide that Plays an Important Role in Parkinson's Disease. Current neuropharmacology, 2025. PMID 40353414. doi:10.2174/011570159X374501250425045109
Suprachiasmatic Nucleus Vasoactive Intestinal Peptide Neurons Mediate Light-induced Transient Forgetting. Neuroscience bulletin, 2025. PMID 40670769. doi:10.1007/s12264-025-01456-7
Vasoactive Intestinal Polypeptide Secreting MS Neuroblastoma. Journal of Indian Association of Pediatric Surgeons, 2024. PMID 39691933. doi:10.4103/jiaps.jiaps_104_24

Questions

Research-grade VIP is supplied for laboratory research use only, and reputable suppliers sell it as a research chemical rather than as a therapeutic product. It is not an FDA-approved drug and is not intended for human or veterinary consumption. Buyers are expected to be researchers or laboratories using the compound in controlled in vitro or preclinical settings, and the research-use-only statement should appear in writing on both the listing and the certificate of analysis.

Pricing varies widely by quantity, purity specification and the depth of analytical testing included with the lot. The main cost driver is not the synthesis itself but the analytics: third-party mass spectrometry, lot-specific HPLC and net peptide content determination all add per-batch expense. A listing that is dramatically cheaper than comparable options is usually cheaper because one of those tests was skipped or because a generic certificate is being reused across lots.

Vasoactive Intestinal Peptide is catalogued under CAS 37221-79-7, with the molecular formula C147H237N43O43S and an average molecular weight of approximately 3,326 Da. It is a 28-amino-acid, C-terminally amidated peptide with the sequence HSDAVFTDNYTRLRKQMAVKKYLNSILN. Human, porcine and rat VIP share the identical sequence, so a listing that gives a different CAS number is likely describing a fragment or an analog.

Lyophilised VIP is stored desiccated and frozen, typically at minus 20 degrees Celsius for working stock and colder for long-term retention, protected from light and moisture. The dry state dramatically slows the oxidation and deamidation reactions that degrade the peptide in aqueous solution. Aliquoting on receipt limits repeated freeze-thaw cycles, which are a common and avoidable cause of batch-to-batch variability in assay results.

Match three things: the CAS number, the stated sequence and the mass spectrometry result on the lot-specific certificate of analysis. The observed mass should be consistent with an average molecular weight near 3,326 Da for the native 28-mer. The lot number printed on the vial must match the lot number on the certificate, and the certificate should be publicly verifiable rather than a generic document reused across the whole catalogue item.

Net peptide content states what percentage of the physical powder in the vial is actually peptide, with the remainder being counterion salt such as trifluoroacetate, bound water and other non-peptide mass. It is a different measurement from HPLC purity, which describes the proportion of peptide-related material in the chromatogram. A vial can report 98% HPLC purity and still contain significantly less than 98% peptide by weight, which is why both figures are needed.

No. Real Peptides supplies research-use-only compounds with third-party COAs and purity documentation. Product pages and support cover verification, storage and handling of sealed vials, and ordering — nothing about laboratory procedure, which is the responsibility of the purchasing researcher and their institution.

Aviptadil is the international nonproprietary name for synthetic Vasoactive Intestinal Peptide, so the underlying 28-amino-acid sequence is the same molecule. The distinction is regulatory and pharmaceutical rather than chemical: aviptadil refers to VIP formulated and investigated as a drug product under clinical study conditions, while research-grade VIP is a laboratory reagent supplied for in vitro and preclinical work. Research-grade material is not a substitute for, or equivalent to, an investigational drug product.

Research reports a native VIP plasma half-life on the order of minutes, attributed largely to rapid enzymatic cleavage by circulating peptidases. Because of that, a substantial part of the published pharmacology uses stabilised analogs, modified sequences or alternative delivery approaches rather than the unmodified peptide. For in vitro receptor-binding and cyclic AMP signalling work, the short systemic half-life is generally not the limiting variable.

VIP binds the VPAC1 and VPAC2 receptors, both class B G-protein-coupled receptors, and interacts with the PAC1 receptor at lower affinity. Receptor binding drives Gs-protein coupling, which activates adenylate cyclase, elevates intracellular cyclic AMP and in turn activates protein kinase A. This cyclic AMP pathway is the shared mechanism behind the smooth muscle, immunological and circadian findings the literature describes.

RESEARCH USE ONLY · NOT EVALUATED BY THE FDA