DSIP (Delta Sleep-Inducing Peptide)
DSIP Structure, Sequence and Physical Properties
DSIP has the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu: nine residues, molecular weight 848.8 Da, formula C35H48N10O15. It is strongly acidic, unusually glycine-rich, contains a single tryptophan and has neither cysteine nor methionine.
Key facts
- Sequence
- H-Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu-OH
- Single-letter
- WAGGDASGE
- Residues
- 9
- Molecular weight
- 848.8 Da
- Molecular formula
- C35H48N10O15
- Acidic residues
- Asp5, Glu9
- Glycines
- Three (positions 3, 4 and 8)
- Cysteine / methionine
- Neither present
Reading the sequence
In single-letter code the peptide is WAGGDASGE: tryptophan, alanine, glycine, glycine, aspartate, alanine, serine, glycine, glutamate. Three of nine residues are glycine and two are acidic. There is no basic residue anywhere in the sequence, which is unusual and gives the molecule a distinctly negative character at physiological pH.
What all that glycine does
Glycine has no side chain, only a hydrogen. It is the most conformationally flexible residue available, and three of them in a nine-residue peptide produce a molecule with very little structural constraint. Where proline-rich peptides such as Semax and Selank are rigid, DSIP is close to the opposite — a highly flexible chain with few internal preferences. Flexible peptides sample many conformations, which complicates any attempt to infer a binding mode.
Research material referenced
DSIP 5mg — third-party HPLC tested
A strongly acidic peptide
Aspartate at position 5 and glutamate at position 9 carry negative charges at physiological pH, with no lysine or arginine to offset them. That makes DSIP one of the more acidic research peptides in common circulation, and it has practical consequences: net charge drives solubility, and behaviour will differ markedly between an acidic diluent such as bacteriostatic water at pH 5.7 and a neutral buffer.
The single tryptophan
Tryptophan at position 1 is the only aromatic residue, and it is the reason DSIP can be quantified spectrophotometrically at all — tryptophan is the strongest natural absorber near 280 nm. One tryptophan gives a usable but modest signal. It is also mildly photosensitive, which is a minor argument for protecting solutions from prolonged light exposure.
What is absent
No cysteine, so no disulfide chemistry and no reducing agent needed. No methionine, so the +16 Da oxidation that dominates handling for MOTS-c and Semax does not apply. The main chemical liabilities are hydrolysis and, given aspartate adjacent to glycine, the possibility of aspartate-related rearrangement — a known degradation route in Asp-Gly containing sequences, though DSIP has Asp-Ala rather than Asp-Gly.
Why the flexibility matters scientifically
A peptide with no rigid elements and no identified receptor is a hard target for structural work. There is no bound conformation to solve, because there is nothing established to bind to. This compounds the receptor problem: even the structural approach that sometimes suggests a target is unavailable here.
Quick reference
| Property | Value |
|---|---|
| Sequence | WAGGDASGE |
| Length | 9 residues |
| Molecular weight | 848.8 Da |
| Formula | C35H48N10O15 |
| CAS | 62568-57-4 |
| UNII | YN28Z5YZ73 |
| PubChem CID | 68816 |
| INN | Emideltide |
Extended research context
The DSIP (Delta Sleep-Inducing Peptide) deep dive
Deep dive: a name that was a hypothesis, not a finding
In 1977 the Schoenenberger-Monnier group in Basel electrically stimulated the thalamus of a sleeping rabbit, collected blood draining from its brain, isolated a peptide fraction, and reported that administering it into the ventricles of awake rabbits produced delta-wave EEG activity. They named it delta sleep-inducing peptide. By the standards of the time this was careful, imaginative work, and they followed it properly - the 1978 Pflugers Archiv paper reported sequence, synthesis and activity of the synthetic nonapeptide rather than stopping at a suggestive fraction. The problem is not the original research. It is that a name recording a hypothesis has been read ever since as a summary of established pharmacology, and almost nobody checks whether it was earned.
Deep dive: the three things that are missing
A proposed endogenous peptide becomes accepted biology by a recognisable route. The gene is located. The precursor protein is characterised. A receptor is identified, giving a mechanism and a testable target. DSIP has completed none of these in nearly fifty years. The receptor gap is the most disabling - without one there is no mechanism to test, no dose-response to build, no antagonist to design, and no way to establish that an observed effect runs through the proposed pathway at all. The gene gap is the hardest to explain away: modern genomics located MOTS-c inside a short open reading frame nested within the mitochondrial 12S rRNA gene, sequence already annotated as something else. That a peptide described in 1977 still has no identified gene in any genome is a substantive observation, not an accident of effort.
Deep dive: why 519 papers is not 519 confirmations
DSIP has roughly 519 indexed PubMed records - more than Selank's 135 or Semax's 231. Publication volume tracks how interesting a question is, not how well it has been answered. A tractable question generates a burst of work and then stops; a question that resists resolution generates papers indefinitely, each a further attempt rather than a further confirmation. Kovalzon's 2006 review in the Journal of Neurochemistry states the field's own assessment in its title: a still unresolved riddle. Reading any individual DSIP paper without that context invites mistaking activity for consensus.
Research applications
- ▸Historical study of humoral sleep-factor hypotheses
- ▸Electroencephalography and delta-wave research methodology
- ▸Structure-activity work on flexible, acidic short peptides
- ▸Comparative work on peptides lacking identified receptors
- ▸Analytical method development for tryptophan-containing peptides
Handling checklist
- ✓Store lyophilised material cold, dry and protected from light
- ✓No reducing agent needed — the sequence contains no cysteine
- ✓No methionine oxidation to expect; a +16 Da satellite warrants explanation
- ✓Protect from prolonged light — the single tryptophan is mildly photosensitive
- ✓Expect pH-dependent solubility; the peptide is strongly acidic with no basic residue
- ✓Aliquot to avoid repeated freeze-thaw cycles
Common research-handling mistakes
Learnt from thousands of researcher orders across our UK labs.
✗ Treating the name as evidence of the effect
Fix: The name records a 1977 hypothesis from a single rabbit EEG study. It is not a summary of established pharmacology.
✗ Citing the 1977 paper as proof DSIP induces sleep
Fix: It reports delta-wave EEG activity in rabbits after intraventricular administration — a narrower claim than inducing sleep, in one species, by a route that bypasses every normal barrier.
✗ Assuming DSIP is an established endogenous human peptide
Fix: No gene has been identified in any species, no precursor characterised and no receptor found.
✗ Reading 519 papers as 519 confirmations
Fix: Volume reflects an unresolved question attracting sustained attempts, not accumulated confirmation.
✗ Making any sleep claim about supplied material
Fix: The evidence does not support it and a therapeutic claim about research material is what MHRA enforcement targets.
Continue researching
Peer-reviewed guides, comparators and matched reference materials.
Related questions researchers ask
- What is DSIP?
- Does DSIP actually induce sleep?
- How was DSIP discovered?
- Does DSIP have a receptor?
- What are delta waves?
- Is DSIP approved anywhere?
Frequently asked questions
- Is DSIP charged?
- Negatively. It carries aspartate and glutamate with no basic residue to offset them, making it strongly acidic at physiological pH.
- Can DSIP be quantified at 280 nm?
- Yes, via its single tryptophan — a usable but modest signal, since one aromatic residue absorbs less than several.
- Does DSIP form disulfide bonds?
- No. There is no cysteine in the sequence.
Primary sources & clinical trials
Peer-reviewed research and registered trials from PubMed, ClinicalTrials.gov, PubChem, FDA and NIH. All links open in a new tab and point to the primary source, so every claim can be verified at origin.
- PubChemPubChem · Delta sleep-inducing peptide (CID 68816)pubchem.ncbi.nlm.nih.gov
- PubMedSchoenenberger GA et al., DSIP XI: sequence, synthesis and activity — Pflügers Arch 1978 (PMID 568769)pubmed.ncbi.nlm.nih.gov
- PubMedSchoenenberger GA et al., Characterization of a delta-EEG (sleep)-inducing peptide — PNAS 1977 (PMID 265572)pubmed.ncbi.nlm.nih.gov
- PubMedKovalzon VM, Delta sleep-inducing peptide (DSIP): a still unresolved riddle — J Neurochem 2006 (PMID 16539679)pubmed.ncbi.nlm.nih.gov
- PubMedPubMed — DSIP literaturepubmed.ncbi.nlm.nih.gov
- RefMHRA — Medicines and Healthcare products Regulatory Agencygov.uk
- GuidelineGoogle — Creating helpful, reliable, people-first contentdevelopers.google.com
Written and reviewed by
Jack Muncaster · Founder, UK Peptides
Jack founded UK Peptides in Manchester after repeatedly receiving research compounds with missing or recycled paperwork. He is responsible for supplier selection, batch release decisions and the content published in this research library. Every article here is sourced to primary literature and every product page to a signed third-party certificate.
More DSIP (Delta Sleep-Inducing Peptide) articles
- DSIP CAS Number and Chemical IdentityDSIP CAS is 62568-57-4, PubChem CID 68816, UNII YN28Z5YZ73, and its INN is emideltide. Identifiers for checking a certificate against the literature.
- DSIP Storage, Stability and ReconstitutionNo cysteine or methionine, so the usual degradation routes do not apply. What a strongly acidic, glycine-rich sequence needs instead.
- DSIP in the Published LiteratureAbout 519 indexed PubMed records across nearly fifty years, and a central claim still unresolved. Why volume of publication is not weight of evidence.
- DSIP Regulatory StatusDSIP holds no marketing authorisation anywhere. It has an INN, emideltide, which is a naming decision rather than an approval — a distinction worth knowing.
- What Is DSIP? A Research OverviewDSIP is a nonapeptide isolated from rabbit blood in 1977 and named for an observed EEG effect. No gene, precursor or receptor has ever been identified.
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