This is a working overview of freeze-thaw, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-06-26 and is reviewed periodically as new material appears.
Two related forms circulate in technical discussion under the same family name. The original version carries a drug affinity complex (DAC) that binds covalently to serum albumin after administration, and this linkage substantially extends circulation time. A second form, frequently written as modified GRF(1-29) or CJC-1295 without DAC, lacks that linker and clears much faster. The naming is a frequent source of confusion because the shorthand CJC-1295 can refer to either form depending on the source. Reports sometimes fail to specify which variant was studied.
The peptide backbone includes a D-alanine at position two, which resists cleavage by dipeptidyl peptidase IV, and several other substitutions that reduce degradation. Its molecular weight is roughly 3.4 kDa without the linker and about 3.6 kDa with it. The molecule is water soluble and is normally supplied as a lyophilized powder. Precise sequence and mass values depend on which variant is described, so technical documents usually state the exact form being referenced.
Reports on this compound commonly follow serum growth hormone and insulin-like growth factor 1 across defined time windows. Protocols differ in sampling frequency, assay platform, and participant characteristics, which makes direct comparison between publications difficult. Some work focuses on pulsatile release patterns instead of average concentrations. Whether repeated exposure alters endogenous hormone rhythms over long periods remains an open question, and the formal literature is thinner than the volume of informal commentary implies.
Once in circulation, the peptide binds the growth hormone-releasing hormone receptor displayed on pituitary somatotroph cells. Receptor activation couples to Gs proteins, elevates intracellular cyclic AMP, and drives protein kinase A signaling inside the cell. That cascade increases discharge of growth hormone into the bloodstream. The analog therefore operates through a receptor pathway that already exists for the body's own releasing hormone, rather than through an engineered artificial target.
| Property | Value | Notes |
|---|---|---|
| Molecular weight (no linker) | ~3.37 kDa | Calculated from peptide sequence |
| Molecular weight (with linker) | ~3.65 kDa | Includes albumin-binding moiety |
| Appearance | White to off-white powder | Typically lyophilized |
| Solubility | Soluble in water | Also dissolves in aqueous buffers |
| Common synonyms | Modified GRF(1-29), DAC:GRF | Usage varies by source |
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.
Reported half-lives differ widely between the two variants and between species. Values for the albumin-binding form are usually expressed in days, while the unconjugated form is measured in minutes to a few hours. Sampling schedules, assay sensitivity, and route of administration all influence the numbers, which limits direct comparison across studies. Whether sustained receptor occupancy produces different downstream effects from pulsatile stimulation remains an open question in the published work. Claims about relative potency should therefore be read alongside the specific study design that produced them.
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.
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.
In 2018, Bio-Rad Laboratories filed a lawsuit against 10x Genomics stating that their linked-read technology infringed on three patents which had been licensed from Bio-Rad at the University of Chicago. Bio-Rad was awarded a sum of $23,930,716 by a jury. The 10x Genomics filed a motion for judgement as a matter of law (JMOL) but were denied in 2019, and the court proceedings concluded in 2020. Following this lawsuit, 10x Genomics discontinued their linked-read assay. An exception was made for linked-read products which had already been sold by the company prior to the lawsuit, allowing 10x Genomics to continue to provide those researchers with services such as support and warranty maintenance for this technology.
The cell-mediated response to the virus and to vectors is poorly characterised, and has been largely ignored in the literature as recently as 2005. Clinical trials using an AAV2-based vector to treat haemophilia B seem to indicate that targeted destruction of transduced cells may be occurring. Combined with data that shows that CD8+ T-cells can recognise elements of the AAV capsid in vitro, it appears that there may be a cytotoxic T lymphocyte response to AAV vectors. Cytotoxic responses would imply the involvement of CD4+ T helper cells in the response to AAV and in vitro data from human studies suggests that the virus may indeed induce such responses, including both Th1 and Th2 memory responses. A number of candidate T cell stimulating epitopes have been identified within the AAV capsid protein VP1, which may be attractive targets for modification of the capsid if the virus is to be used as a vector for gene therapy. There are several steps in the AAV infection cycle, from infecting a cell to producing new infectious particles:
β-pleated sheet structures are made from extended β-strand polypeptide chains, with strands linked to their neighbours by hydrogen bonds. Due to this extended backbone conformation, β-sheets resist stretching. β-sheets in proteins may carry out low-frequency accordion-like motion as observed by the Raman spectroscopy and analyzed with the quasi-continuum model. A β-helix is formed from repeating structural units consisting of two or three short β-strands linked by short loops. These units "stack" atop one another in a helical fashion so that successive repetitions of the same strand hydrogen-bond with each other in a parallel orientation. See the β-helix article for further information. In lefthanded β-helices, the strands themselves are quite straight and untwisted; the resulting helical surfaces are nearly flat, forming a regular triangular prism shape, as shown for the 1QRE archaeal carbonic anhydrase at right. Other examples are the lipid A synthesis enzyme LpxA and insect antifreeze proteins with a regular array of Thr sidechains on one face that mimic the structure of ice.
Tranexamic acid is frequently used following major trauma. Tranexamic acid is used to prevent and treat blood loss in a variety of situations, such as dental procedures, heavy menstrual bleeding, and surgeries with high risk of blood loss. Tranexamic acid has been found to decrease the risk of death due to any cause in people who have significant bleeding due to trauma. It is most effective if taken within the first three hours following major trauma. It also decreases the risk of death if given within the first three hours of brain injury.
Vaginal films are soluble, thin sheets of medication that are inserted into the vagina where they dissolve and release the substances. Typical uses include delivery of contraceptive substances or antibiotics for infections. These films are inserted by simply pushing them into the vagina with one’s fingers. There they dissolve quickly upon interaction with natural vaginal fluids. Bioadhesives are substances that naturally stick to live tissue. Currently, studies are being done on bioadhesives adhering to cervical mucous membranes to allow for an extended release period. The drug would be released with mucus to create a localized treatment with high effectiveness. This is anticipated to be highly useful for treatment of cervical cancer. Bioadhesives can come in multiple forms, such as films, tablets, or gels. The appeal of bioadhesives is that they take advantage of the mucous environment surrounding the cervix and utilize it to benefit the drug delivery mechanism.
Sources: en.wikipedia.org
The predecessor of modern countercurrent chromatography theory and practice was countercurrent distribution (CCD). The theory of CCD was described in the 1930s by Randall and Longtin. Archer Martin and Richard Laurence Millington Synge developed the methodology further during the 1940s. Finally, Lyman C. Craig introduced the Craig countercurrent distribution apparatus in 1944 which made CCD practical for laboratory work. CCD was used to separate a wide variety of useful compounds for several decades.
Calmodulin-like protein 5 is a protein that in humans is encoded by the CALML5 gene. This gene encodes a novel calcium binding protein expressed in the epidermis and related to the calmodulin family of calcium binding proteins. Functional studies with recombinant protein demonstrate it does bind calcium and undergoes a conformational change when it does so. Abundant expression is detected only in reconstructed epidermis and is restricted to differentiating keratinocytes. In addition, it can associate with transglutaminase 3, shown to be a key enzyme in the terminal differentiation of keratinocytes. Human CALML5 genome location and CALML5 gene details page in the UCSC Genome Browser. Overview of all the structural information available in the PDB for UniProt: Q9NZT1 (Human Calmodulin-like protein 5) at the PDBe-KB.
Small clusters of cas genes are often located next to CRISPR repeat-spacer arrays. Collectively the 93 cas genes are grouped into 35 families based on sequence similarity of the encoded proteins. 11 of the 35 families form the cas core, which includes the protein families Cas1 through Cas9. A complete CRISPR-Cas locus has at least one gene belonging to the cas core. CRISPR-Cas systems fall into two classes. Class 1 systems use a complex of multiple Cas proteins to degrade foreign nucleic acids. Class 2 systems use a single large Cas protein for the same purpose. Class 1 is divided into types I, III, and IV; class 2 is divided into types II, V, and VI. The 6 system types are divided into 33 subtypes. Each type and most subtypes are characterized by a "signature gene" found almost exclusively in the category. Classification is also based on the complement of cas genes that are present. Most CRISPR-Cas systems have a Cas1 protein. The phylogeny of Cas1 proteins generally agrees with the classification system, but exceptions exist due to module shuffling. Many organisms contain multiple CRISPR-Cas systems suggesting that they are compatible and may share components. The sporadic distribution of the CRISPR-Cas subtypes suggests that the CRISPR-Cas system is subject to horizontal gene transfer during microbial evolution.
Laboratory testing in the United States is subject to federal regulation. Clinical laboratories performing testing are overseen by the Centers for Medicare and Medicaid Services (CMS) utilizing national standards established under the Clinical Laboratory Improvement Amendments (CLIA). The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) assist CMS in this process. CMS ensures the integrity of laboratories performing testing via inspections and consistent oversight, bolstered with proficiency testing by accredited organizations. CLIA authorizes regulation of laboratories that conduct testing, not the individuals who order the tests or receive test results. All laboratories performing DTC testing must obtain CLIA certification and maintain compliance with national standards.
Sources: en.wikipedia.org
PABA is an intermediate in the synthesis of folate by bacteria, plants, and fungi. Many bacteria, including those found in the human intestinal tract such as E. coli, generate PABA from chorismate by the combined action of the enzymes 4-amino-4-deoxychorismate synthase and 4-amino-4-deoxychorismate lyase. Plants produce PABA in their chloroplasts, and store it as a glucose ester (pABA-Glc) in their tissues. The malarial protozoan Plasmodium only make PABA when necessary, preferring to get it from the surroundings if able to. Some bacteria, including a few found in the human microbiome, are unable to make PABA for themselves but can use PABA to make folate. A few are very efficient at the PABA-to-folate conversion despite not making their own PABA. Sulfonamide drugs are structurally similar to PABA, and their antibacterial activity is due to their ability to interfere with the conversion of PABA to folate by the enzyme dihydropteroate synthetase. Thus, bacterial growth is limited through folate deficiency.
The cell membrane can form different types of "supramembrane" structures such as caveolae, postsynaptic densities, podosomes, invadopodia, focal adhesions, and different types of cell junction. These structures are usually responsible for cell adhesion, communication, endocytosis and exocytosis. They are composed of specific proteins, such as integrins and cadherins. They can be visualized by electron microscopy or fluorescence microscopy.
BIA Separations was formed in 1998 by a group of scientists in Ljubljana, Slovenia to commercialize a new chromatographic resin based on monolith technology. Monolithic resin was developed independently by three different laboratories in late 1980s led by Hjertén, Švec and Tennikova. The company was one of the few Slovenian companies to receive venture capital funding at that time-Horizonte Venture Management realizing the potential of monoliths made the initial investment in the company. During that year, BIA Separations released its first commercial product marketed under the trade name of CIM (Convective Interaction Media). The new technique was named HPMC (High Performance Monolith Chromatography). During the 1999 and 2000s, the company promoted this new platform technology to the scientific and business community and registered several patents. In 2007 the company headquarters moved to Villach, Austria. In 2011 BIA Separations entered a strategic partnership with Japan Synthetic Rubber Corporation, a Japanese company producing synthetic materials. A strategic partnership agreement with Showa Denko K.K. (SDK) was signed in 2012.
Acids play important roles in the human body. The hydrochloric acid present in the stomach aids digestion by breaking down large and complex food molecules. Amino acids are required for synthesis of proteins required for growth and repair of body tissues. Fatty acids are also required for growth and repair of body tissues. Nucleic acids are important for the manufacturing of DNA and RNA and transmitting of traits to offspring through genes. Carbonic acid is important for maintenance of pH equilibrium in the body. Human bodies contain a variety of organic and inorganic compounds, among those dicarboxylic acids play an essential role in many biological behaviors. Many of those acids are amino acids, which mainly serve as materials for the synthesis of proteins. Other weak acids serve as buffers with their conjugate bases to keep the body's pH from undergoing large scale changes that would be harmful to cells. The rest of the dicarboxylic acids also participate in the synthesis of various biologically important compounds in human bodies.
MIPOL1 (Mirror Image Polydactyly 1), also known as CCDC193 (Coiled-coil domain containing 193), is a protein that in humans is encoded by the MIPOL1 gene. Mutation of this gene is associated with mirror-image polydactyly (also known as Laurin-Sandrow syndrome.) in humans, which is a rare genetic condition characterized by mirror-image duplication of digits. MIPOL1 is also known as CCDC193 (Coiled-coil domain containing 193). The MIPOL1 gene is located at 14q13.3-q21.1 on the plus strand, spanning base pairs 37,197,888 to 37,579,207 (in the human GRCh38 primary assembly, length: 381,320 base pairs), consisting of 15 exons and 11 introns. Some notable genes in its neighborhood include SLC25A21 (mutation of this gene causes synpolydactyly) and FOXA1. MIPOL1 has at least 15 known splice isoforms produced by alternative splicing. The unmodified MIPOL1 protein isoform 1 in humans has an isoelectric point of 5.6 and molecular weight 51.5 kDa. Relative to other human proteins, MIPOL1 consists of unusually low amounts of Proline and Glycine and higher amounts of Glutamic acid and Glutamine.
Sources: en.wikipedia.org
No. It is a synthetic analogue modeled on the first 29 residues of human GHRH. The substitutions and any linker are laboratory modifications rather than features of the endogenous peptide.
Early development used the albumin-binding form, and a shorter variant was later discussed under the same label. Because the two differ in half-life and handling, ambiguity arises whenever a source omits the variant designation.
The compound derives from that fragment but is not identical to it. The parent fragment lacks the stabilizing substitutions, so its degradation rate and duration of action differ noticeably.
It acts on the growth hormone-releasing hormone receptor found on pituitary somatotroph cells. Activation of that receptor triggers growth hormone release through a cyclic AMP dependent pathway.