Drosocin
A fruit-fly antimicrobial peptide with a sugar attached — non-lytic, it jams the bacterial ribosome rather than bursting the cell. A research compound, not a drug
Drosocin is the fruit fly's proline-rich antimicrobial peptide, and it has two features that make it stand out. First, it is non-lytic: like the honeybee peptide apidaecin, drosocin does not break bacterial membranes but is taken inside and jams the ribosome, the cell's protein-making machine, arresting it at stop codons so finished proteins cannot be released. Second, it is a glycopeptide — it carries a sugar attached to a specific threonine, and unusually that O-glycosylation makes the peptide more active, not less. Drosocin is mainly active against Gram-negative bacteria such as E. coli and Klebsiella, and because it targets an internal machine rather than the membrane it is gentle on host cells and not hemolytic. The short peptide is a favourite model for studying how sugars and proline-rich sequences tune antibacterial activity, and engineered versions (for example with hydroxyproline substitutions) have been made to resist the body's enzymes. Drosocin is a research peptide; it is not an approved medicine and has not been given to people as a treatment.
No established human dose Details ↓
Recommended Dosing
No established human dose
Drosocin is a fruit-fly research peptide; it has not been given to people as a treatment. The work is in bacteria, cultured cells and fruit-fly models, often with synthetic, glycosylated or engineered analogs, at experimental amounts that do not carry over to people.
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What is it?
When a fruit fly is infected, it floods its hemolymph with antimicrobial peptides, and drosocin — first described in 1993 — is one of the key ones. It is short, just nineteen residues, and rich in proline, placing it in the proline-rich antimicrobial peptide (PrAMP) family alongside the honeybee's apidaecin. Its defining chemical feature is that it is glycosylated: a sugar (an alpha-GalNAc, sometimes extended to a disaccharide) is attached to the threonine at position 11. Remarkably, this O-glycosylation increases drosocin's antibacterial activity, the opposite of what one might expect, which has made the peptide a central model for studying how sugar modifications shape antimicrobial function.
Drosocin's mechanism was pinned down in 2023. Like apidaecin, drosocin is non-lytic: rather than disrupting membranes, it is taken into Gram-negative bacteria and binds inside the ribosome's nascent-peptide exit tunnel, where it lets translation reach a stop codon and then traps the class-1 release factor RF1, freezing the ribosome and blocking the completion of protein synthesis. This made drosocin the second confirmed member of the 'type II' PrAMP class. A cryo-electron-microscopy structure showed exactly how the attached sugar helps: the glycosylation makes extra contacts with the ribosomal RNA, changing its local shape and strengthening binding — a direct structural explanation for why the glycopeptide is more active. Interestingly, though drosocin and apidaecin act the same way, they grip the ribosome differently: apidaecin depends on just a few C-terminal residues, whereas drosocin relies on residues spread along the whole peptide.
Chemistry studies have mapped the rest of the rules. The threonine-linked sugar is preferred over a serine-linked one, and the rigidity the sugar provides can be mimicked by substituting prolines, yielding active non-glycosylated analogs. Stereochemistry matters too: the natural (L) amino acids are needed for the peptide to get into bacteria, even though once inside the machinery it can be copied with mirror-image sugars. And because short linear peptides are quickly chewed up by the body's enzymes, drosocin analogs with hydroxyproline substitutions were engineered to survive far longer in serum while keeping — even improving — their activity against E. coli and Klebsiella, all without toxicity or hemolysis to human cells.
Drosocin also turns out to do more than fight bacteria. In fruit-fly models of blood-cell (hematopoietic) tumors, drosocin and the companion peptide cecropin A were taken up into tumour cells and triggered their death by apoptosis, apparently by targeting phosphatidylserine exposed on the tumour surface, without harming normal cells — an anti-tumor role for an antimicrobial peptide that researchers suggest could inform low-side-effect anti-cancer strategies. The fly's drosocin gene even encodes a second defence peptide, and natural sequence differences steer which pathogens each one fights.
Through all of this, drosocin remains a research peptide. No published study has given it to people as a treatment, it is not approved anywhere, and material sold online under this name is an unregulated research chemical. Nothing here is a dose or a therapy; this page records what the published science says.
Mechanism of Action
Drosocin is a short, O-glycosylated, proline-rich fruit-fly antimicrobial peptide (a 'type II' PrAMP) that is NON-LYTIC: bacteria import it and it binds the ribosome exit tunnel, trapping release factor RF1 and arresting ribosomes at stop codons (it also binds the chaperone DnaK). Mainly Gram-negative, not hemolytic; its threonine-linked sugar boosts activity.
Fruit-fly host defense (glyco-PrAMP)
A 19-residue proline-rich peptide from Drosophila hemolymph, O-glycosylated at threonine 11 — a sugar that increases its activity (PMIDs 36997646, 28656506).
Ribosome / translation-termination block
Imported by bacteria, binds the ribosomal exit tunnel and traps release factor RF1, arresting ribosomes at stop codons — a non-lytic 'type II' PrAMP mechanism; also binds DnaK (PMIDs 36997647, 25617693).
Gram-negative spectrum; anti-tumor in flies
Mainly active against Gram-negative bacteria with low host toxicity; in fruit-fly models it (with cecropin A) also kills blood-cell tumours by apoptosis (PMIDs 28656506, 40136638).
Published Research
These are studies of drosocin read from their PubMed records on November 7, 2026: the discovery of its translation-termination mechanism and a cryo-EM structure of the glycosylated peptide on the ribosome; chemistry studies comparing its glycosylated forms and the role of the threonine sugar and stereochemistry; an engineering study giving it serum stability; and a fruit-fly study of its anti-tumor activity. The evidence is in bacteria, cells and fruit-fly models; drosocin has not been given to people as a treatment.
Drosocin and cecropin A kill blood-cell tumors in fruit flies
In fruit-fly mutants that develop blood-cell (hematopoietic) tumors, drosocin and cecropin A produced by the fat body were taken up into tumour cells and triggered their death by apoptosis, depending on the innate-immune pathway and apparently targeting phosphatidylserine exposed on the tumour surface, without harming normal cells — suggesting antimicrobial peptides as low-side-effect anti-cancer leads (a fruit-fly study).
Drosocin arrests ribosomes at stop codons (a type II PrAMP)
Drosocin was shown to inhibit protein synthesis by arresting ribosomes at stop codons and sequestering class-1 release factors — the same non-lytic mechanism as apidaecin, making drosocin the second 'type II' PrAMP; yet a comprehensive mutant library showed drosocin grips the ribosome via residues spread throughout the peptide, unlike apidaecin's few key C-terminal residues (an in-vitro study).
Structural basis for how glycosylated drosocin jams the ribosome
Cryo-electron-microscopy structures of O-glycosylated drosocin on the ribosome showed it binds the nascent-peptide exit tunnel and traps release factor RF1, like apidaecin; crucially, the attached sugar makes extra contacts with the ribosomal RNA, changing its local conformation and providing a structural explanation for why the glycosylation boosts activity (a structural study).
Comparing the natural glycosylated forms of drosocin
Comparing drosocin carrying a single sugar versus a disaccharide showed the disaccharide form was somewhat less potent against Gram-negative bacteria, indicating the distal sugar and chain length tune activity; the glycosylation did not change the peptide's overall not hemolytic, non-cytotoxic character or make it stimulate inflammatory cytokines (an in-vitro study).
The role of the glycosylated threonine and stereochemistry in drosocin
A threonine-linked sugar made drosocin more active than a serine-linked one, apparently by providing a rigid conformation that could be mimicked by substituting prolines to give an active non-glycosylated analog; natural (L) amino acids were required for the peptide to enter bacteria, while the chaperone DnaK was confirmed as a binding target (an in-vitro study).
Hydroxyproline substitutions give drosocin serum stability
Substituting certain prolines of a non-glycosylated drosocin with trans-4-hydroxyproline made the peptide several times more stable in mouse serum and improved its activity against E. coli and Klebsiella, while remaining non-toxic to human cell lines and not hemolytic — a stability-engineering study toward systemic use.
No Established Human Dose
Drosocin is a fruit-fly research peptide; it has not been given to people as a treatment. The work is in bacteria, cultured cells and fruit-fly models, often with synthetic, glycosylated or engineered analogs, at experimental amounts that do not carry over to people. No regulator has approved any dose, and no published human dose exists, so no amount is printed here.
What this rests on: PMID 36997647, PMID 28656506, PMID 24164265.
Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Drosocin is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
Unknown: no human dose of Drosocin has been established (see No Established Human Dose below), so there is no amount to work out. The reconstitution calculator does the arithmetic for any vial, water and dose.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Drosocin, before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Drosocin stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Drosocin. What the human studies gave and how is set out under No Established Human Dose.
What to expect, and when
How long it stays in the body: a half-life of short for the natural peptide; hydroxyproline-substituted analogs are several times more stable in serum. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Drosocin. Results reported in the studies are under Published Research.
Source: half-life: PMID 24164265.
Side effects, and when to stop or get help
From the Side Effects section: No human adverse-event data exist: no published study has administered drosocin to people; Unlike membrane-disrupting peptides, drosocin is non-lytic, not hemolytic and non-toxic to human cell lines in the lab (PMIDs 28656506, 24164265) — research findings, not human data; Its spectrum is mainly Gram-negative and uptake-dependent, so activity can be lost if bacteria change the transporters that import it; Material sold online as 'drosocin' is an unregulated research chemical of unverified content. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Drosocin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Drosocin is a research peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status and its biology”).
Interactions
Unknown: a PubMed search for human interaction studies of Drosocin (reviewed 2026-11-07) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Drosocin products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: Research Chemical (Not a drug: Drugs@FDA and the openFDA label endpoint hold no record, and FDA GSRS and ChEMBL hold no approved-drug record for drosocin (searched November 7, 2026)). Sport: Not on the 2026 List.
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
Drosocin is a research peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status and its biology.
Contraindications & Cautions
Drosocin has no approved use and no label. These points reflect its research status.
Legal Status
Drosocin is a fruit-fly antimicrobial peptide used as a research compound; it is not a drug and is not approved in any country.
Frequently Asked Questions
?What is drosocin?
A proline-rich antimicrobial peptide from the fruit fly (Drosophila melanogaster), about 19 amino acids long and O-glycosylated at a threonine, first described in 1993 (PMID 36997646).
?How does it work?
It is non-lytic: bacteria import it and it binds the ribosome, trapping release factor RF1 and arresting ribosomes at stop codons to block protein-synthesis completion (a 'type II' PrAMP, like apidaecin); its attached sugar strengthens this binding (PMIDs 36997647, 36997646).
?Why does the sugar matter?
Unusually, drosocin's O-glycosylation increases its antibacterial activity: the sugar makes extra contacts with the ribosomal RNA, and the threonine-linked sugar is more effective than a serine-linked one (PMIDs 36997646, 25617693).
?Is it approved or available to buy?
No. Drosocin is not a medicine, has no FDA application or label, and is approved nowhere. Material sold online as drosocin is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [animal] Hirata M, et al. "Anti-Tumor Effects of Cecropin A and Drosocin Incorporated into Macrophage-like Cells Against Hematopoietic Tumors in Drosophila mxc Mutants." Cells, 2025;14(6). PMID: 40136638.
- [mechanism] Mangano K, et al. "Inhibition of translation termination by the antimicrobial peptide Drosocin." Nat Chem Biol, 2023;19(9):1082-1090. PMID: 36997647.
- [mechanism] Koller TO, et al. "Structural basis for translation inhibition by the glycosylated drosocin peptide." Nat Chem Biol, 2023;19(9):1072-1081. PMID: 36997646.
- [mechanism] Lele DS, et al. "Comparing naturally occurring glycosylated forms of proline rich antibacterial peptide, Drosocin." Glycoconj J, 2017;34(5):613-624. PMID: 28656506.
- [mechanism] Lele DS, et al. "Understanding the importance of glycosylated threonine and stereospecific action of Drosocin, a Proline rich antimicrobial peptide." Eur J Med Chem, 2015;92:637-47. PMID: 25617693.
- [mechanism] Knappe D, et al. "Hydroxyproline substitutions stabilize non-glycosylated drosocin against serum proteases without challenging its antibacterial activity." Protein Pept Lett, 2014;21(4):321-9. PMID: 24164265.
- [other] Drosocin is a proline-rich antimicrobial peptide from the fruit fly Drosophila melanogaster, produced in the hemolymph on bacterial challenge, first described by Bulet and colleagues (J Biol Chem, 1993) as an inducible antibacterial peptide carrying an O-glycosylated residue. Its structure, glycosylation and mechanism are described in the studies carded on this page (read November 7, 2026).
- [other] US FDA, Drugs@FDA and the openFDA label endpoint, searched November 7, 2026: no application and no label record for drosocin. It is a fruit-fly research antimicrobial peptide, not a drug; FDA GSRS and ChEMBL hold no approved-drug record for it.
Sources & Citations
The six studies carded above were read from their PubMed records on November 7, 2026. Drosocin's fruit-fly origin, its 19-residue O-glycosylated proline-rich structure, its non-lytic 'type II' ribosome-targeting mechanism (trapping release factor RF1 at stop codons, with the sugar strengthening binding), its Gram-negative spectrum and not hemolytic character, its DnaK binding and serum-stabilised analogs, and its anti-tumor activity in fruit flies are from the studies carded here; the discovery is Bulet et al. (J Biol Chem, 1993). The absence of US approval or a drug record from Drugs@FDA, openFDA, FDA GSRS and ChEMBL was checked the same day. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.