Maleimide chemistry comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-01-05. Numbers and descriptions here follow the published literature rather than marketing material.
Two related forms appear under the CJC-1295 name. The simpler analogue, commonly written as modified GRF(1-29), carries the four substitutions but no additional conjugation. The second form attaches a maleimidopropionic acid linker to a lysine residue, a modification frequently called the drug affinity complex. That linker reacts with the free thiol on serum albumin to form a covalent bond. Because albumin has a long residence time in blood, the conjugated peptide stays in circulation far longer than the unconjugated analogue.
Receptor level activity follows the canonical GHRH pathway. The peptide binds the GHRH receptor, a class B G protein coupled receptor on somatotroph cells of the anterior pituitary. Binding raises intracellular cyclic AMP, which promotes calcium entry and the release of growth hormone into the bloodstream. Because the molecule acts at the same receptor as the endogenous hormone, its effect is superimposed on the natural pulsatile rhythm rather than replacing it. Whether sustained receptor occupation leads to desensitization is not fully settled.
CJC-1295 belongs to a family of synthetic peptides modeled on growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. The compound is built from the first twenty-nine amino acids of the natural human sequence, a fragment that retains full receptor binding capacity. Native growth hormone-releasing hormone is degraded quickly in circulation, so the fragment alone has limited practical value. Early work therefore focused on chemical modifications that preserve receptor binding while slowing enzymatic breakdown. The result is a molecule described in the literature as a long-acting analog of the natural hormone.
Two forms circulate under the CJC-1295 name, and they differ by a single appended group. The version without a drug affinity complex carries four substitutions along the peptide chain, including a D-alanine near the amino terminus and replacements at three other positions. These changes block the enzyme dipeptidyl peptidase IV and remove a methionine residue that is prone to oxidation. The modified fragment is frequently labeled MOD GRF 1-29. Naming conventions are inconsistent across informal sources, which is a common source of confusion.
The second form adds a maleimide-bearing linker to the lysine at the carboxyl end. This group reacts with cysteine-34 on circulating serum albumin, forming a covalent bond that keeps the peptide in the bloodstream for far longer. ConjuChem developed the molecule as a way to extend the action of a peptide without frequent administration. The albumin attachment is the defining structural feature of the drug affinity complex version. Whether continuous exposure produces effects distinct from shorter pulses remains an unresolved research question.
| Property | Value | Notes |
|---|---|---|
| Peptide class | Synthetic GHRH analogue | Built on a 29 residue sequence |
| Primary target | GHRH receptor (GHRHR) | Class B G protein coupled receptor |
| Unconjugated half life | Minutes | Limited by protease degradation |
| Key modification | Four residue substitutions | Positions 2, 8, 15 and 27 |
| Common synonym | Modified GRF(1-29) | Usually denotes the form without DAC |
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.
The drug affinity complex is a maleimidopropionic acid group attached to a lysine side chain. It reacts with the free thiol of cysteine-34 on circulating albumin, forming a covalent bond. This conjugation keeps the peptide in the bloodstream and shields it from rapid renal filtration and proteolysis. Reported circulation half-lives for the albumin-bound form fall in the range of roughly six to nine days in early human studies.
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.
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.
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.
sulfur amino acid metabolic processes DNA methylation methionine metabolic processes methionine biosynthetic processes methylation S-adenosylmethionine (SAM) cycle homocysteine catabolic processes folic acid metabolic processes oxidation-reduction processes negative regulation of cystathionine beta-synthase activity.
Clean-in-place systems are typically used to remove fouling from membranes after extensive use. The CIP process may use detergents, reactive agents such as sodium hypochlorite and acids and alkalis such as citric acid and sodium hydroxide (NaOH). Sodium hypochlorite (bleach) must be removed from the feed in some membrane plants. Bleach oxidizes thin-film membranes. Oxidation will degrade the membranes to a point where they will no longer perform at rated rejection levels and have to be replaced. Bleach can be added to a sodium hydroxide CIP during an initial system start-up before spirally-wound membranes are loaded into the plant to help disinfect the system. Bleach is also used to CIP perforated stainless steel (Graver) membranes, as their tolerance for sodium hypochlorite is much higher than a spirally-wound membrane. Caustics and acids are most often used as primary CIP chemicals. Caustic removes organic fouling and acid removes minerals. Enzyme solutions are also used in some systems for helping remove organic fouling material from the membrane plant. The pH and temperature are important to a CIP program. If pH and temperature are too high the membrane will degrade and flux performance will suffer. If pH and temperature are too low, the system simply will not be cleaned properly. Every application has different CIP requirements. e.g. a dairy reverse osmosis (RO) plant most likely will require a more rigorous CIP program than a water purification RO plant. Each membrane manufacturer has their own guidelines for CIP procedures for their product.
The ion extraction efficiency (β) can be optimized by increasing the voltage of both repeller and acceleration. Since the ionization cross section depends on the chemical nature of the sample and the energy of ionizing electrons a standard value of 70 eV is used. At low energies (around 20 eV), the interactions between the electrons and the analyte molecules do not transfer enough energy to cause ionization. At around 70 eV, the de Broglie wavelength of the electrons matches the length of typical bonds in organic molecules (about 0.14 nm) and energy transfer to organic analyte molecules is maximized, leading to the strongest possible ionization and fragmentation. Under these conditions, about 1 in 1000 analyte molecules in the source are ionized. At higher energies, the de Broglie wavelength of the electrons becomes smaller than the bond lengths in typical analytes; the molecules then become "transparent" to the electrons and ionization efficiency decreases. The effective ionizing path length (L) can be increased by using a weak magnetic field. But the most practical way to increase the sample current is to operate the ion source at higher ionizing current (Ie).
Sources: en.wikipedia.org
== Medical uses == Cetacaine is a benzocaine-based anesthetic that also contains other active ingredients that include butamben and tetracaine hydrochloride. The main use for this drug is to produce anesthesia to mucous membranes to numb and help control the pain in that area. The spray form of Cetacaine is also used to help prevent gagging in the patient. The anesthetic effect of Cetacaine can be expected to take effect in about 30 seconds and last between 30–60 minutes depending on location and application amount. Cetacaine can and has been used for surgeries that include bronchi, ear, esophagus, larynx, mouth, nose, pharynx, rectal, and vaginal procedures. These procedures can include periodontal treatment, pre-probing, pre-scaling/root planning procedures, pre-injection, and laser dentistry.
== Further reading == Hunt, Chris; et al. (August 28, 2023). "Shanidar et ses fleurs? Reflections on the palynology of the Neanderthal 'Flower Burial' hypothesis". Journal of Archaeological Science. 159 105822. Bibcode:2023JArSc.159j5822H. doi:10.1016/j.jas.2023.105822. S2CID 261325698. Pettitt, Paul; White, Mark (2012). The British Palaeolithic: hominin societies at the edge of the Pleistocene world. London: Routledge. ISBN 978-0-415-67454-6. Romagnoli, Francesca; Rivals, Florent; Benazzi, Stefano (2022). Updating Neanderthals: Understanding Behavioural Complexity in the Late Middle Palaeolithic. Academic Press. ISBN 978-0-12-821429-9. Stringer, C.; Gamble, C. (1993). In search of the Neanderthals. Thames and Hudson. ISBN 0-500-05070-8. Sykes, Rebecca Wragg (2020). Kindred: Neanderthal Life, Love, Death and Art. London: Bloomsbury Sigma. ISBN 978-1-4729-3749-0.
In the 2010s, Ells tried to diversify the company by creating or acquiring several subsidiaries. These subsidiaries offered very different cuisines compared to their parent company. Examples include soul food (Soul Daddy), Asian cuisine (ShopHouse Southeast Asian Kitchen), pizza (Pizzeria Locale), and burgers (Tasty Made). In 2023, Chipotle had also tried incorporating California-inspired bowls into the Farmesa Fresh Eatery concept. The few test locations were not a financial success, and all concepts were discontinued. In 2011, Steve Ells was a judge for the TV show America's Next Great Restaurant and investor of ANGR Holdings, the company that would launch the winning concept's restaurants. Chipotle agreed to purchase Ells' investment in ANGR at his cost, provide support for ANGR operations, and invest a total of $2.3 million in cash contributions. The winning concept, Soul Daddy, was quickly closed after operating for eight weeks. In September 2011, Chipotle opened an Asian fast-casual concept restaurant named ShopHouse Southeast Asian Kitchen in Washington, D.C. The company said the new restaurant "would follow the Chipotle service format and its focus on 'food with integrity' in ingredients". Chipotle's plan was to start with only one store and see how the restaurant worked out before expanding the concept. On July 29, 2016, the company announced the opening of its first Tasty Made burger restaurant in the fall.
Sources: en.wikipedia.org
The names are often used interchangeably in casual writing, but they are not strictly identical. Modified GRF(1-29) refers to the unconjugated analogue carrying only the four substitutions. The version sold as CJC-1295 with DAC includes the albumin binding linker and clears much more slowly.
DAC stands for drug affinity complex, a term describing the maleimidopropionic acid linker. This group forms a covalent bond with the cysteine residue on serum albumin after administration. The resulting adduct is what extends the circulating half life from minutes to days.
No. It is entirely synthetic and does not correspond to any known endogenous peptide. The design starts from human growth hormone releasing hormone and introduces deliberate substitutions. Any biological effect comes from mimicking the natural hormone at its receptor.
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.