Maleimide chemistry is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-01-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
Binding to GHRH receptors on pituitary somatotroph cells triggers cyclic AMP signaling and stimulates growth hormone synthesis and release. Because the peptide acts upstream of the pituitary, effects are mediated through endogenous growth hormone rather than direct receptor activation in peripheral tissues. Increases in insulin-like growth factor 1 are generally described as a downstream consequence. Most published human exposure data come from small early-stage studies, and the clinical significance of the pharmacokinetic profile remains incompletely characterized.
CJC-1295 is a synthetic analogue of growth hormone-releasing hormone, built on the 29-amino-acid GHRH(1-29) fragment. Four substitutions distinguish it from the natural sequence: D-alanine at position 2, glutamine at position 8, alanine at position 15, and leucine at position 27. These changes reduce enzymatic cleavage and extend the peptide's persistence in circulation. The compound is discussed in two forms, one carrying a drug affinity complex and one without it.
Four amino acid substitutions separate the modified backbone from the parent GRF(1-29) sequence. These changes reduce recognition by dipeptidyl peptidase IV and related proteases, extending the interval before degradation. Development work in this area sought longer-acting GHRH analogs for endocrine investigation. Published descriptions treat the substitution set as a defining property of the core sequence, while the albumin-binding linker is described separately as an optional addition to that same backbone.
CJC-1295 is a synthetic peptide analog of growth hormone-releasing hormone, constructed on the 29-amino-acid fragment designated GRF(1-29). The name began as an internal development code during the 1990s and later spread through research supply catalogs and discussion forums. The molecule does not occur in nature; its sequence is engineered rather than isolated from tissue. Two related compounds are sold under this single label, and they differ by one appended chemical group that strongly influences how long the peptide remains in circulation.
| Property | Value | Notes |
|---|---|---|
| Physical form | Lyophilized white powder | Supplied as a freeze-dried solid for research use |
| Molecular weight | Approximately 3,647 Da (DAC form) | Lower for the variant lacking the albumin-binding moiety |
| Solubility | Soluble in water and aqueous buffer | Typically dissolved in sterile or bacteriostatic water |
| Typical storage temperature | −20 °C or below | Dry powder, desiccated and protected from light |
| Common analytical method | Reversed-phase HPLC with mass spectrometry | Used for purity estimation and identity confirmation |
Enzymatic protection is a separate mechanism from plasma protein binding. The four substitutions in the backbone reduce recognition by dipeptidyl peptidase IV, which normally cleaves the natural hormone within minutes. Without the reactive group, this resistance still yields only a short window of activity, generally reported in the range of tens of minutes. With it, reported half-lives in early human work extended to several days. The size of that gap is the main practical distinction between the two materials.
Both forms act at the pituitary receptor for growth hormone-releasing hormone and increase growth hormone output, which in turn raises insulin-like growth factor 1. A long-acting analog produces sustained rather than pulsatile stimulation, and the physiological consequences of that pattern are not fully settled. Published human data on the extended form remain limited, and much of what circulates in discussion traces to early company reports rather than independent replication. How sustained exposure affects normal feedback remains an open question.
The distinguishing feature of the DAC form is a maleimide-containing group that reacts with the free thiol of cysteine-34 on human serum albumin. This reaction forms a covalent bond without enzymatic assistance, and it takes place after the peptide enters the bloodstream. Because albumin is abundant and long-lived, the attached peptide is carried through circulation far longer than an unmodified fragment would survive. The chemistry is a deliberate pharmacokinetic strategy rather than a change to receptor activity.
Batch-to-batch consistency depends on solid-phase peptide synthesis and subsequent purification. Coupling efficiency, resin choice, and cleavage conditions all affect the final profile. Counter-ion content and moisture can shift the apparent mass of a batch. Documentation typically includes a certificate of analysis with chromatograms and spectra. Independent verification by a second laboratory is sometimes requested. Whether a given certificate reflects the actual vial contents depends on chain of custody. Analytical methods themselves carry uncertainty that should be stated alongside results.
Lyophilized material is typically stored at minus twenty degrees Celsius or lower. Keeping the vial dry and protected from light preserves peptide integrity. Repeated freeze-thaw cycles can cause aggregation or loss of activity. Once dissolved, solutions are generally kept at two to eight degrees Celsius. Stability data for reconstituted solutions vary, and long-term behavior is not fully established. Working aliquots reduce the number of times a stock container is opened.
Studies in this area generally track growth hormone pulses, insulin-like growth factor 1 concentrations, and occasionally body composition endpoints. Most published human data come from early, small trials, and questions about long-term effects remain open. Whether repeated exposure alters pituitary responsiveness over time is not settled. Analytical work relies on immunoassays for the hormones and on mass spectrometry for the peptide itself, because the two measurements answer different questions.
Binding of the peptide to the growth hormone-releasing hormone receptor on pituitary somatotrophs triggers a G protein coupled cascade that raises cyclic AMP and opens calcium channels. The result is greater secretion of growth hormone into the bloodstream. Because the peptide acts at the same receptor as the natural hypothalamic hormone, its effect is amplified pulse size rather than an entirely separate release pathway. Receptor binding alone does not determine the response, since somatostatin tone and other inputs modulate the final output.
Laboratory handling centers on minimizing exposure to water, heat and oxygen before use. Working solutions are typically prepared in sterile water or a mild buffer, and any residual particulate matter is removed by filtration. When the powder dissolves slowly, a small proportion of acetonitrile or dilute acetic acid is sometimes added as a co-solvent. Containers are kept sealed and desiccated between uses. Records of lot number, reconstitution date and storage conditions support later comparison of results across experiments.
Identity and purity are established with reversed phase high performance liquid chromatography coupled to mass spectrometry. The chromatographic step separates the target peptide from truncated sequences and deletion products, while the mass measurement confirms the expected molecular weight to within a fraction of a dalton. Because the two common variants differ by the presence of the linker, mass alone can distinguish them in the unconjugated state. Amino acid analysis and peptide mapping are used when sequence level confirmation is required.
Lyophilized material is generally stable for extended periods when held at minus twenty degrees Celsius or below and protected from moisture and light. In solution the peptide is more labile; bond hydrolysis, aggregation and oxidation of susceptible residues all proceed faster at ambient temperature. Repeated freeze and thaw cycles should be avoided because they promote clumping and loss of soluble material. The conjugated variant adds a further consideration, since the maleimide group can hydrolyze in aqueous buffer and lose its ability to react with albumin.
Apoptosis. During programmed cell death the ICE/ced-3 family of proteases (one of the interleukin-1β-converter proteases) degrade actin into two fragments in vivo; one of the fragments is 15 kDa and the other 31 kDa. This represents one of the mechanisms involved in destroying cell viability that form the basis of apoptosis. The protease calpain has also been shown to be involved in this type of cell destruction; just as the use of calpain inhibitors has been shown to decrease actin proteolysis and the degradation of DNA (another of the characteristic elements of apoptosis). On the other hand, the stress-induced triggering of apoptosis causes the reorganization of the actin cytoskeleton (which also involves its polymerization), giving rise to structures called stress fibers; this is activated by the MAP kinase pathway.
Antihypertensive drugs Anti-anxiety drugs (e.g. benzodiazepines) Antipsychotic drugs Anticonvulsants Non-steroidal anti-inflammatory drugs (e.g. Antihistamine) Opioid Medical marijuana Recreational drugs
"In it, the distress, caused by thirst, to travellers, was alleviated by clusters of rays of the bright eyes of the girls; the rays that were shaming the currents of light, sweet and cold water charged with the strong fragrance of cardamom, clove, saffron, camphor and musk and flowing out of the pitchers (held in) the lotus-like hands of maidens (seated in) the beautiful water-sheds, made of the thick roots of vetiver mixed with marjoram, (and built near) the foot, covered with heaps of couch-like soft sand, of the clusters of newly sprouting mango trees, which constantly darkened the intermediate space of the quarters, and which looked all the more charming on account of the trickling drops of the floral juice, which thus caused the delusion of a row of thick rainy clouds, densely filled with abundant nectar."
large RNA and protein complexes: ribosome, spliceosome, vault large protein complexes: proteasome, DNA polymerase III holoenzyme, RNA polymerase II holoenzyme, symmetric viral capsids, complex of GroEL and GroES; membrane protein complexes: porosome, photosystem I, ATP synthase large DNA and protein complexes: nucleosome centriole and microtubule-organizing center (MTOC) cytoskeleton flagellum nucleolus stress granule germ cell granule neuronal transport granule The mechanisms by which such non-membrane bounded organelles form and retain their spatial integrity have been likened to liquid-liquid phase separation.
Psilocybin's psychedelic effects can be blocked by serotonin 5-HT2A receptor antagonists like ketanserin and risperidone in humans. Activation of serotonin 5-HT2A receptors in layer V of the medial prefrontal cortex (mPFC) and consequent glutamate release in this area has been especially implicated in the hallucinogenic effects of psilocybin and other serotonergic psychedelics. In addition, region-dependent alterations in brain glutamate levels may be related to the experience of ego dissolution. The cryo-EM structures of the serotonin 5-HT2A receptor with psilocin, as well as with various other psychedelics and serotonin 5-HT2A receptor agonists, have been solved and published by Bryan L. Roth and colleagues. Although serotonin 5-HT2A receptor agonism mediates the hallucinogenic effects of psilocybin and psilocin, activation of other serotonin receptors also appears to contribute to these compounds' psychoactive and behavioral effects. Serotonin 5-HT1A receptor activation seems to inhibit the hallucinogenic effects of psilocybin and other psychedelics. Some of psilocybin's non-hallucinogenic behavioral effects in animals can be reversed by antagonists of the serotonin 5-HT1A, 5-HT2B, and 5-HT2C receptors. Psilocybin produces profoundly decreased locomotor and investigatory behavior in rodents, and this appears to be dependent on serotonin 5-HT1A receptor activation but not on activation of the serotonin 5-HT2A or 5-HT2C receptors.
Sources: en.wikipedia.org
== See also == Manhunt (military) 1989 capture of Manuel Noriega, similar event 2003 capture of Saddam Hussein, similar event 2016 recapture of El Chapo, similar event 2026 Jalisco operation, similar event 2026 Iran war, occurred exactly 8 weeks later 2003 Invasion of Iraq Foreign policy of the second Trump administration List of state leaders deposed by foreign powers in the 20th and 21st century
== Selecting discriminatory peptides == Finally, sophisticated normalization methods are used to remove systematic artefacts in the peptide intensity values between LC-MS measurements. Then, discriminatory peptides are identified by selecting the peptides whose normalized intensities are different (e.g., p-value < 0.05) among multiple groups of samples. In addition, newer hybrid mass spectrometers like LTQ OrbiTrap offer the possibility to acquire MS/MS peptide identifications in parallel to the high mass precision measurement of peptides on the MS1 level. This raises the computational challenge for the processing and integration of these two sources of information and has led to the development of novel promising quantification strategies.
== Research == Osemozotan was under development for the treatment of anxiety disorders, generalized anxiety disorder, insomnia, irritable bowel syndrome, and major depressive disorder. It reached phase 2 clinical trials, but as of December 2025, development for all indications has been suspended, with suspension having occurred in May 2014. Besides the preceding indications, osemozotan has also been studied for potential treatment of pain, aggression, obsessive–compulsive disorder, and stimulant use disorder.
=== Education === Humphreys graduated from Chickasha High School (Chickasha, Oklahoma) in 1948. He then attended Colorado College, graduating with his BA in 1952. He attended Seabury-Western Theological Seminary (in Evanston, Illinois), graduating with the MDiv degree in 1955. In 1965, he entered graduate school at Washington University to pursue a PhD in sociology. His dissertation adviser was Lee Rainwater. Humphreys obtained two pre-doctoral research fellowships from the National Institute of Mental Health to fund his dissertation research. He completed his dissertation in 1968, graduating with his PhD in that year. He published the dissertation as Tearoom Trade: Impersonal Sex in Public Places in 1970. His book won the C. Wright Mills Award from the Society for the Study of Social Problems in 1969. Due to the controversy around his research methods and the topic of his research, there was a failed attempt by the chancellor of Washington University to rescind his PhD.
Sources: en.wikipedia.org
The two share the same 29-amino-acid backbone. CJC-1295 carries an additional albumin-binding moiety that markedly extends its residence time in circulation, while the form without that moiety clears faster. Literature sometimes applies the name loosely to either variant.
It has not been approved by major regulatory agencies for any therapeutic indication. Material sold under this name is typically distributed for laboratory research only. Clinical use is not supported by large controlled trials.
Early human studies of the albumin-binding form reported circulation half-lives on the order of several days. The value depends on assay method and study design. Estimates for the form without the binding moiety are considerably shorter.
No. It is a laboratory-synthesized analog built on a fragment of the natural hormone. The natural peptide is shorter-lived and lacks the stabilizing substitutions found in the synthetic version.