Lyophilized powder raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-04-30. Anything still debated is marked as such rather than presented as settled.
CJC-1295 belongs to a class of synthetic peptides modeled on growth hormone releasing hormone, a forty-four amino acid signal produced by the hypothalamus. The compound is built from the first twenty-nine residues of the natural sequence, with four substitutions introduced at positions 2, 8, 15 and 27. These changes were designed to slow enzymatic breakdown while preserving receptor activation. The result is a peptide that is shorter than native GHRH and considerably more resistant to ordinary clearance pathways in circulation.
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.
Research material is normally supplied as a freeze-dried powder in sealed vials. In that state the peptide is comparatively robust, but prolonged exposure to warmth, moisture, or light accelerates degradation. Storage at minus twenty degrees Celsius or lower, with desiccant and protection from light, is the commonly described practice. Vials should be allowed to reach room temperature before opening to limit condensation on the powder. Moisture uptake during handling is a recognized source of variability in later measurements.
Reconstitution is typically performed with sterile water or bacteriostatic water, added slowly against the vial wall. The resulting solution should be clear and colorless; cloudiness or visible particles suggest a problem with the material or the diluent. Once in solution, the peptide is less stable than the dry powder. Refrigerated storage at two to eight degrees Celsius is common for short-term holding, while freezing aliquots is described for longer periods.
Purity is most often assessed by reversed-phase high-performance liquid chromatography, reported as a percentage of total peak area. Identity is confirmed by mass spectrometry, which yields a molecular ion consistent with the expected sequence. Amino acid analysis and peptide mapping provide additional characterization. Reported purity values are method-dependent, so figures from different laboratories are not always directly comparable without details of column, gradient, and detection wavelength.
| 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 |
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.
CJC-1295 is a synthetic peptide modeled on growth hormone-releasing hormone, the hypothalamic signal that prompts the pituitary to release growth hormone. Its sequence corresponds to the first twenty-nine residues of human GHRH, with four substitutions that slow enzymatic breakdown. Early descriptions placed the compound in research on growth hormone deficiency and related conditions, and later literature groups it with the long-acting GHRH analogs. The name appears in both laboratory and popular fitness writing, where it sometimes labels chemically different peptides.
Two related peptides circulate under the CJC-1295 label, and they differ mainly in how long they persist in circulation. The version carrying a drug affinity complex includes a maleimidopropionic acid linker that forms a covalent bond with serum albumin. The other version, usually written as modified GRF(1-29) or tetrasubstituted GRF(1-29), lacks that linker and is cleared quickly. Mixing the two produces inconsistent readings of published half-life values, because the linker rather than the receptor-facing sequence drives most of the difference.
=== Drugs that induce a type 1 diabetes like syndrome === Some medicines can reduce insulin production or damage β cells, resulting in a disease that resembles type 1 diabetes. The antiviral drug didanosine triggers pancreas inflammation in 5 to 10% of those who take it, sometimes causing lasting β-cell damage. Similarly, up to 5% of those who take the anti-protozoal drug pentamidine experience β-cell destruction and diabetes. Several other drugs cause diabetes by reversibly reducing insulin secretion, namely statins (which may also damage β cells), the post-transplant immunosuppressants cyclosporin A and tacrolimus, the leukemia drug L-asparaginase, and the antibiotic gatifloxicin.
Mononuclear cells produce proteases and growth factors to digest the extra-cellular scaffold and allow motility and provide space for the new cells. They also produce NO from inducible nitric oxide synthetase (iNOS), which is essential for arteriogenesis. The bulk of new tissue production is carried by the smooth muscles of the media, which transform their phenotype from a contractile into a synthetic and proliferative one. Important roles are played by actin binding proteins like actin-binding Rho-activating protein (ABRA), cofilin, and thymosin beta 4 which determine actin polymerization and maturation. Integrins and connexins are markedly up-regulated. A key role in this concerted action, which leads to a 2-to-20 fold increase in vascular diameter, depending on species size (mouse versus human), are the transcription factors AP-1, egr-1, carp, ets, by the Rho pathway and by the mitogen activated kinases ERK-1 and -2. In spite of the enormous increase in tissue mass (up to 50-fold), the degree of functional restoration of blood flow capacity is incomplete and ends at 30% of maximal coronary conductance and 40% in the vascular periphery. The process of arteriogenesis can be drastically stimulated by increases in FSS (arterio-venous fistulas) and can be completely blocked by inhibition of NO production, by pharmacological blockade of VEGF-A, and by the inhibition of the Rho-pathway.
== History == The FDA's approval of sildenafil in 1998 was a ground-breaking commercial event for the treatment of ED, with sales exceeding US$1 billion. Subsequently, the FDA approved both vardenafil and tadalafil in 2003. It initially was developed by the biotechnology company ICOS, and then again developed and marketed worldwide by Lilly ICOS, LLC, the joint venture of ICOS Corporation and Eli Lilly and Company. Tadalafil was approved in 2009 in the United States for the treatment of pulmonary arterial hypertension and is under regulatory review in other regions for this condition. In late November 2008, Eli Lilly sold the exclusive rights to commercialize tadalafil for pulmonary arterial hypertension in the United States to United Therapeutics for an upfront payment of $150 million. Tadalafil was discovered by Glaxo Wellcome (now GlaxoSmithKline) under a partnership between Glaxo and ICOS to develop new drugs that began in August 1991. In 1993, the Bothell, Washington, biotechnology company ICOS Corporation began studying compound IC351, a phosphodiesterase type 5 (PDE5) enzyme inhibitor. In 1994, Pfizer scientists discovered that sildenafil, which also inhibits the PDE5 enzyme, caused penile erection in males participating in a clinical study of a heart medicine. Although ICOS scientists were not testing compound IC351 for treating ED, they recognized its potential usefulness for treating that disorder. Soon, in 1994, ICOS received a patent for compound IC351 (structurally unlike sildenafil and vardenafil), and Phase 1 clinical trials began in 1995.
Sources: en.wikipedia.org
Adopted from analytical chemistry, the term top down in proteomics means the separation of intact proteoforms and their subsequent identification, and is agnostic as to how that is achieved. Currently, there are two analytical approaches that enable proteome assessments to different extents: Integrative or Integrated TDP (iTDP; current usually utilizing routine high resolution/sensitivity two-dimensional gel electrophoresis tightly coupled with liquid chromatography and tandem mass spectrometry (2DE/LC/MS/MS)) or mass spectrometry-intensive TDP (MSi-TDP); while these terms may not yet be widely used, it is important to differentiate between these approaches as they enable quite different depths and comprehensiveness of proteome analysis. Such clear distinction is critical in terms of the transparency, accuracy, and thoroughness of proteome research. As always, it is critical for every study to fully describe the methods used. Thus, although currently most often utilizing 2DE/LC/MS/MS, iTDP is a more general term for the integration of the best available approaches to enable truly comprehensive, deep proteome analyses at the critically necessary level of intact proteoforms.
Sherrill's methods and algorithms are made publicly available to the quantum chemistry community through the open-source quantum chemistry program Psi, developed by his group and collaborators worldwide.
Error can be defined as numerical difference between observed value and true value. The experimental error can be divided into two types, systematic error and random error. Systematic error results from a flaw in equipment or the design of an experiment while random error results from uncontrolled or uncontrollable variables in the experiment. In error the true value and observed value in chemical analysis can be related to each other by the equation
Sources: en.wikipedia.org
=== Review of the validity of the AI Cold War narrative === Academics and observers expressed concerns about the validity and soundness of the AI Cold War narrative. Denise Garzia expressed concern in Nature that the AI Cold War narrative will undermine the efforts by the US to establish global rules for AI ethics. Researchers have warned in MIT Technology Review that the breakdown in international collaboration in the area of science because of the threat of the alleged AI Cold War would be detrimental to progress. Additionally, the AI Cold War narrative impacts on many more areas including the planning of supply chains and the proliferation of AI. The dissemination of the AI Cold War narrative could therefore be costly and destructive and exacerbate existing tensions.
Dams – the Aztec in Tenochtitlan constructed great dams during the heyday of the Aztec Empire. Tenochtitlan, the capital of the Aztec empire, was first built on a small island that was located in the western section of Lake Texcoco in 1325 CE. The Aztec created various large artificial islands around the small island using a system that was similar to building the chinampas (floating gardens in the lake that was used to grow food for the cities' population). To provide drinking water to the cities' population of over a quarter of a million inhabitants, the Aztec built a system of dams that separated the salty waters of the lake from the rainwater that was accumulated during periods of heavy rains. The Aztec also used the dam to control the level of water in the lake and prevent their city from being flooded during times of heavy rains. To prevent flooding, the Aztec constructed an inner system of channels that helped to control the water level and held the level steady during flooding and periods of intense rains. Hernán Cortés, and the other Spanish conquistadors, destroyed these engineering marvels that the Aztec had developed during the previous 200 years. Dog breeds – Native American dogs believed to have been bred by indigenous Americans are the xochiocoyotl (coyote), xoloitzcuintli (known as xolo or Mexican hairless), chihuahua, Peruvian Hairless Dog, the Carolina Dog, Canadian Eskimo Dog, and the Alaskan Malamute.
=== EC 2.3.2: Aminoacyltransferases === EC 2.3.2.1: D-glutamyltransferase EC 2.3.2.2: γ-glutamyltransferase EC 2.3.2.3: lysyltransferase EC 2.3.2.4: Now classified as EC 4.3.2.9, γ-glutamylcyclotransferase EC 2.3.2.5: glutaminyl-peptide cyclotransferase EC 2.3.2.6: leucyltransferase EC 2.3.2.7: aspartyltransferase EC 2.3.2.8: arginyltransferase EC 2.3.2.9: agaritine γ-glutamyltransferase EC 2.3.2.10: UDP-N-acetylmuramoylpentapeptide-lysine N6-alanyltransferase EC 2.3.2.11: alanylphosphatidylglycerol synthase EC 2.3.2.12: peptidyltransferase EC 2.3.2.13: protein-glutamine g-glutamyltransferase EC 2.3.2.14: D-alanine γ-glutamyltransferase EC 2.3.2.15: glutathione γ-glutamylcysteinyltransferase EC 2.3.2.16: lipid II:glycine glycyltransferase EC 2.3.2.17: N-acetylmuramoyl-L-alanyl-D-glutamyl-L-lysyl-(N6-glycyl)-D-alanyl-D-alanine-diphosphoundecaprenyl-N-acetylglucosamine:glycine glycyltransferase EC 2.3.2.18: N-acetylmuramoyl-L-alanyl-D-glutamyl-L-lysyl-(N6-triglycine)-D-alanyl-D-alanine-diphosphoundecaprenyl-N-acetylglucosamine:glycine glycyltransferase EC 2.3.2.19: ribostamycin:4-(γ-L-glutamylamino)-(S)-2-hydroxybutanoyl-[BtrI acyl-carrier protein] 4-(γ-L-glutamylamino)-(S)-2-hydroxybutanoate transferase EC 2.3.2.20: cyclo(L-leucyl-L-phenylalanyl) synthase EC 2.3.2.21: cyclo(L-tyrosyl-L-tyrosyl) synthase EC 2.3.2.22: cyclo(L-leucyl-L-leucyl) synthase EC 2.3.2.23: E2 ubiquitin-conjugating enzyme EC 2.3.2.24: (E3-independent) E2 ubiquitin-conjugating enzyme EC 2.3.2.25: N-terminal E2 ubiquitin-conjugating enzyme EC 2.3.2.26: HECT-type E3 ubiquitin transferase EC 2.3.2.27: RING-type E3 ubiquitin transferase EC 2.3.2.28: L-allo-isoleucyltransferase EC 2.3.2.29: aspartate/glutamate leucyltransferase EC 2.3.2.30: L-ornithine Nα-acyltransferase EC 2.3.2.31: RBR-type E3 ubiquitin transferase EC 2.3.2.32: cullin-RING-type E3 NEDD8 transferase EC 2.3.2.33: RCR-type E3 ubiquitin transferase EC 2.3.2.34: E2 NEDD8-conjugating enzyme EC 2.3.2.35: capsaicin synthase EC 2.3.2.36: RING-type E3 ubiquitin transferase (cysteine targeting)
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.
Cool, dark, and dry conditions are standard, with storage at minus twenty degrees Celsius or below. Desiccant and sealed vials limit moisture uptake. Repeated warming and cooling of the container is generally avoided.