If you have been reading about freeze-thaw and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-08-04. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Lyophilised powder is the usual supplied form. The material is hygroscopic, so vials are typically equilibrated to room temperature before opening in order to prevent condensation on the contents. Long-term storage is generally described at minus twenty degrees Celsius or colder, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they promote aggregation and loss of soluble material. A reconstituted solution is considerably less stable than the dry powder and is normally kept refrigerated for short periods only.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography combined with mass spectrometry. The chromatographic separation resolves the target peptide from truncation products and from species carrying oxidised residues, while mass measurement confirms the expected molecular mass. Because the two common variants differ by roughly 280 daltons, a mass determination distinguishes them unambiguously. Purity is often quoted as a percentage of total peak area, although that figure depends on the detection wavelength and the integration method applied.
| Property | Value | Notes |
|---|---|---|
| Class | Synthetic peptide | GHRH receptor agonist |
| Sequence length | 29 amino acids | Derived from human GHRH |
| Molecular weight | About 3368 Da without linker | Albumin-binding form is heavier |
| Appearance | White to off-white lyophilized powder | Common form for research reference material |
| Typical storage | -20 °C or below, desiccated | Protect powder from light and moisture |
Stability depends heavily on physical state. A lyophilized powder kept dry, desiccated, and shielded from light typically holds its integrity for months to years at minus twenty degrees Celsius, and longer at minus eighty. Once dissolved, the peptide becomes far more vulnerable, since peptide bond hydrolysis, oxidation of susceptible residues, and aggregation all proceed faster in solution. Buffers near neutral pH are generally gentler than strongly acidic or alkaline conditions. Repeated freeze-thaw cycles and exposure to air-liquid interfaces during vigorous mixing cause losses that are easy to overlook.
Verification matters because research peptides vary widely in quality. A certificate of analysis is only as reliable as the method behind it, and a single chromatographic trace reveals little about counter-ions, residual solvents, or water content. Independent laboratories commonly pair mass confirmation with chromatographic purity and, where relevant, quantify water along with acetate or trifluoroacetate content. Reported purity figures are not standardized across suppliers, so a stated value such as ninety-eight percent is not directly comparable unless the analytical method, column, and detection wavelength accompany it.
CJC-1295 acts at the growth hormone-releasing hormone receptor, a G-protein-coupled receptor found on somatotroph cells in the anterior pituitary. Binding triggers a rise in cyclic AMP and calcium entry, which promotes release of stored growth hormone. Because the peptide mimics the body's own releasing hormone, it amplifies existing secretory pulses rather than driving continuous output. The size of the response therefore depends partly on the subject's own hormonal rhythm and feedback state.
The attached maleimide group explains the unusual duration of the DAC version. After injection it reacts with the thiol of cysteine-34 on serum albumin, forming a stable covalent bond. The resulting conjugate is too large for rapid kidney filtration and is shielded from many peptidases. Reported half-lives for this form reach several days, whereas the version without the group is cleared in roughly half an hour. That gap is the main pharmacological difference between the two.
Downstream of growth hormone, the liver and other tissues increase production of insulin-like growth factor 1, a mediator of many growth-promoting effects. Studies have documented elevated levels of both hormones after dosing, and the rise from the long-acting form persists longer than that produced by shorter-acting analogues. What remains unclear is whether sustained elevation of these markers translates into meaningful clinical benefit, and whether prolonged exposure carries risks that short trials could not detect.
Bidentate ligands bind to metal ions forming a chelate ring. Ligands of higher denticity form two or more chelate rings. Ethylenediamine, 2,2'-bipyridine, and 1,10-phenanthroline form C2N2M chelate rings. Just like in organic chemistry, 5- and 6-membered chelate rings predominate.
== History == The first scholars to propose that there are three primary colors for painters were Scarmiglioni (1601), Savot (1609), de Boodt (1609) and Aguilonius (1613). From these, the most influential was the work of Franciscus Aguilonius (1567–1617), although he did not arrange the colors in a wheel. Jacob Christoph Le Blon was the first to apply the RYB color model to printing, specifically mezzotint printing, and he used separate plates for each color: yellow, red and blue plus black to add shades and contrast. In 'Coloritto', Le Blon asserted that “the art of mixing colours…(in) painting can represent all visible objects with three colours: yellow, red and blue; for all colours can be composed of these three, which I call Primitive”. Le Blon added that red and yellow make orange; red and blue, make purple; and blue and yellow make green (Le Blon, 1725, p6). In the 18th century, Moses Harris advocated that a multitude of colors can be created from three "primitive" colors – red, yellow, and blue. Mérimée referred to "three simple colours (yellow, red, and blue)" that can produce a large gamut of colors and details. "United in pairs, these three primitive colours give birth to three other colours as distinct and brilliant as their originals; thus, yellow mixed with red, gives orange; red and blue, violet; and green is obtained by mixing blue and yellow" (Mérimée, 1839, p245).
== SP == Sp (p) Special Spring tide (nautical charts) (i) sine prole (Latin, "without offspring") SP (i) Security Police Self-Propelled Shore Patrol (s) Spain (FIPS 10-4 country code) (i) Start Point Strong Point spa – (s) Spanish language (ISO 639-2 code) SPA - Single Page Application SPAAG – (a) Self-Propelled Anti-Aircraft Gun SPAC - Saratoga Performing Arts Center SPACECOM – (p) (U.S.) Space Command SPAL – (a) Società Polisportiva Ars et Labor ("Art & Labor Sports Club", with the "SP" from Italian and "AL" from Latin), Italian football club Spaser – (a) Surface plasmon amplification by stimulated emission of radiation SPC – (i) Secretariat of the Pacific Community SPCA - Society for the Prevention of Cruelty to Animals SPCO – (i) Single-Pole Change Over SPD (i) Shimano Pedaling Dynamics Sozialdemokratische Partei Deutschlands (Social Democratic Party of Germany) SPDT – (i) Single-Pole Double-Throw SPEAC – (a) Stop Primate Experiments at Cambridge (later became SPEAK) SPECTRE – SPecial Executive for Counter-intelligence, Terrorism, Revenge and Extortion S.P.E.A.R.
Sources: en.wikipedia.org
Pakistani officials also added that they had destroyed an ammunition depot and headquarters of 205 Corps brigade headquarters in Kandahar. According to Afghan local sources, Taliban were moving tanks, military equipment, and weapons from Takhar and Badakhshan to Kabul amid the conflict with Pakistan. They further add that outposts and checkpoints in parts of northern Afghanistan had been evacuated following the redeployment of Taliban forces from these areas to border regions. UN High Commissioner for Refugees (UNHCR) state that an estimated 115,000 people in Afghanistan and around 3,000 people in Pakistan have been displaced as result of border clashes. Afghans in several cities sent pictures and messages to an Afghan media outlet saying that they were threatened and forced by Taliban to participate in demonstration against Pakistan. Some Afghans in Bamyan province said local businessmen were warned that if they did not participate in the protests, "their shops would be sealed." On 6 March, armed clashes resumed along the border between Taliban forces and Pakistani border guards. Taliban officials said that they had launched an attack on Kharlachi border crossing in Dandpatan district of Paktia province, while sharing pictures of their attack. The Taliban-led Afghan Ministry of Defense said, over the previous 24 hours, Taliban forces had attacked 28 locations in the border areas of Kandahar, Nangarhar, Kunar, Khost, Paktia, and Paktika provinces, killing 109 Pakistani soldiers and injuring 148 others.
In Ancient Greece, the Hippocratic Corpus described the anatomy of the skeleton and muscles. The 2nd century physician Galen of Pergamum compiled classical knowledge of anatomy into a text that was used throughout the Middle Ages. In the Renaissance, Andreas Vesalius (1514–1564) pioneered the modern study of human anatomy by dissection, writing the influential book De humani corporis fabrica. Anatomy advanced further with the invention of the microscope and the study of the cellular structure of tissues and organs. Modern anatomy uses techniques such as magnetic resonance imaging, computed tomography, fluoroscopy and ultrasound imaging to study the body in unprecedented detail.
=== Peptide mimics === Peptides that bind extra-cellular PCSK9 have been explored as potential PCSK9 inhibitors in preclinical studies. One of these, Merck's enlicitide decanoate (formerly known as MK-0616), was approved for medical use in the United States in July 2026. According to one reviewer, it "promises to be a blockbuster cholesterol-lowering drug".
== External links == Gerritsen VB (September 2003). "The Plant Kingdom's sloth". Protein Spotlight. Swiss Institute of Bioinformatics (SIB). Rubisco plods along at a mere three molecules per second... To bypass such slothfulness, plants synthesize a gross amount of Rubisco, sometimes up to 50% of their total protein content!
Sources: en.wikipedia.org
Natural GHRH is degraded quickly by dipeptidyl peptidase-4 and related enzymes, giving it a half-life measured in minutes. CJC-1295 carries substitutions that slow that breakdown, so it stays intact longer. Both act at the same pituitary receptor and produce the same class of signal.
The label was first attached to the albumin-binding form during early development work. A shorter analog without the linker later became known by the same name in informal use. Published papers normally state which version was studied, so the methods section resolves the ambiguity.
It is a synthetic peptide rather than a steroid, and it does not occur naturally in the body. Its sequence is derived from a hypothalamic hormone called growth hormone-releasing hormone. It works as a receptor agonist rather than as a replacement for that hormone.
Chromatography reports how much material elutes as a single peak but does not confirm what that material is. Mass spectrometry supplies the molecular mass, which is characteristic of a given sequence and its modifications. Together the two methods support both a purity figure and an identity claim.