A practical reference on DAC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-07-30 and is reviewed periodically as new material appears.
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.
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.
Reverse-phase high-performance liquid chromatography is the standard tool for purity assessment. The technique separates the target peptide from truncated or modified byproducts. Mass spectrometry confirms molecular weight and supports sequence verification. Electrospray ionization and matrix-assisted laser desorption are both used. Amino acid analysis provides an independent check on composition. Purity values are commonly reported as area percentage from the chromatogram. Residual trifluoroacetate and water content are also measured in many quality programs.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off white powder | Typical lyophilized form |
| Water solubility | Soluble | May need a small organic co-solvent |
| Purity assessment | Chromatographic peak area | Most certificates report a percentage figure |
| Storage temperature | Minus 20 C or lower | Dry, dark, sealed container |
| Identity check | Electrospray mass spectrometry | Compared against theoretical mass |
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.
The dividing feature between the two forms is a maleimide-based drug affinity complex, abbreviated DAC. In the DAC-bearing version, a linker attaches the peptide to serum albumin after administration, and that association slows removal from plasma. The version lacking DAC appears in catalogs as MOD GRF(1-29) or tetrasubstituted GRF(1-29). Because informal writing treats both as one item, comparisons drawn from such sources routinely blend measurements taken from two molecules with substantially different behavior.
The compound emerged from work at a Canadian biotechnology firm in the early 2000s. Early human studies examined its effect on growth hormone and insulin-like growth factor 1 in healthy volunteers and in people with HIV-associated fat redistribution. Reports described sustained increases in both markers after a single injection. Development did not advance to regulatory approval, and the clinical programme was later discontinued. The molecule is now encountered mainly as a research chemical rather than a marketed medicine.
Two forms circulate in research settings and are frequently confused. One carries the drug affinity complex and is often written as CJC-1295 with DAC; the other lacks that group and is usually called modified GRF(1-29). The two share the same core sequence but differ sharply in how long they persist in blood. Products labelled only as CJC-1295 normally refer to the version carrying the complex. Documentation that omits the distinction leaves the intended molecule ambiguous.
CJC-1295 is a synthetic peptide built as a long-acting analogue of growth hormone-releasing hormone. Its backbone matches the first twenty-nine residues of the natural human hormone, with four amino acid substitutions added to slow enzymatic breakdown. A reactive maleimide group, commonly termed the drug affinity complex, allows the peptide to attach to circulating albumin after administration. That albumin attachment keeps the molecule in the bloodstream for an extended period instead of being cleared within minutes.
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.
Characterization of this peptide relies on a small set of routine techniques. Reversed-phase high-performance liquid chromatography separates the target from truncated or oxidized by-products and yields a purity estimate when paired with ultraviolet detection near 214 nanometers. Mass spectrometry, either electrospray coupled to liquid chromatography or matrix-assisted laser desorption, confirms that the observed mass matches the value calculated for the expected sequence. Amino acid analysis, and enzymatic digestion followed by fragment mapping, are used when the sequence itself rather than the mass requires verification.
== Risk management and regulations == Aflatoxin B1 exposure is best managed by measures aimed at preventing contamination of crops in the field, post-harvest handling, and storage, or via measures aimed at detecting and decontaminating contaminated commodities or materials used in animal feed. For instance, biological decontamination involving the use of a single bacterial species, Flavobacterium aurantiacum has been used to remove aflatoxin B1 from peanuts and corn. Several countries around the world have rules and regulations governing aflatoxin B1 in foods and these include the maximum permitted, or recommended levels of aflatoxin B1 for certain foods.
== Episode 6: Deja Vu == Matt Lee is a 20-year-old college student who suffers from fainting spells that only occur when he has a sense of Deja Vu, these fainting spells at times can cause his heart to stop all together. Matt states that when he was around 19, one day he just started feeling very light headed and had a sense of Deja Vu then shortly after he blacked out. When he woke back up and realized he had blacked out, he immediately went to the hospital, the next time he fainted had flatlined. Specifically his symptoms include a sense of tingling in his head that is followed by light-headedness, nausea, heart palpitations, loss of control, and then finally the Deja Vu before he faints. Matt is extremely afraid that these random fainting episodes could happen at any time during the day and he might not have someone to help him out, because of these he stays at home as much as he could. He expresses his disappointment in not being able to follow his goals in wanting to study computer science and wanting to find a cure or treatment that would allow him to be “free” again. Matt was admitted into Johns Hopkins Hospital for in depth testing of all his symptoms, the only definitive diagnosis known is the fact that Matt is experiencing Syncope. Syncope are essentially fainting spells that are caused by a decrease of blood reaching the brain, the only question is what is causing the decreased blood flow along with the other symptoms.
May 31: Decree regarding the admission of women to the role of Foreign Trade Advisor. June 14: The issuance of a passport no longer requires a husband's authorization for a married woman. September 30: Decree establishing a Higher Council for Child Protection. 1938
The meat of a lamb is taken from the animal between one month and one year old, with a carcass weight of between 5.5 and 30 kg (12 and 66 lb). This meat generally is more tender than that from older sheep and appears more often on tables in some Western countries. Hogget and mutton have a stronger flavour than lamb because they contain a higher concentration of species-characteristic fatty acids and are preferred by some. Mutton and hogget also tend to be tougher than lamb (because of connective tissue maturation) and are therefore better suited to casserole-style cooking, as in Lancashire hotpot, for example. Lamb is often sorted into three kinds of meat: forequarter, loin, and hindquarter. The forequarter includes the neck, shoulder, front legs, and the ribs up to the shoulder blade. The hindquarter includes the rear legs and hip. The loin includes the ribs between the two. Lamb chops are cut from the rib, loin, and shoulder areas. The rib chops include a rib bone; the loin chops include only a chine bone. Shoulder chops are usually considered inferior to loin chops; both kinds of chops are usually grilled. Breast of lamb (baby chops) can be cooked in an oven. Leg of lamb is a whole leg; saddle of lamb is the two loins with the hip. Leg and saddle are usually roasted, though the leg is sometimes boiled. Forequarter meat of sheep, as of other mammals, includes more connective tissue than some other cuts, and, if not from a young lamb, is best cooked slowly using either a moist method, such as braising or stewing, or by slow roasting or American barbecuing.
The median lethal dose (LD50) of a venom is the dose required to kill half the members of a tested population after a specified test duration. A lower LD50 number indicates increased toxicity. There are four methods for administering the LD50 test: Subcutaneous: Venom is injected into the fatty layer beneath the skin. Intravenous: Venom is injected directly into a vein. Intramuscular: Venom is injected into a muscle. Intraperitoneal: Venom is injected into the abdominal cavity. The most commonly tested methods are subcutaneous and intravenous injections, using mice. Subcutaneous is the most applicable to actual bites: Only large Bitis or extremely large Bothrops or Crotalus specimens are able to deliver a bite that is truly intramuscular, and intravenous injections are extremely rare in actual bites. Mixing dry venom with 0.1% bovine serum albumin in saline gives more consistent test results than mixing with saline alone. Wayne C Hodgson et al. stated in 2002: "Historically, the lethality of snake venoms has been based on murine LD50 studies. Due to ethical reasons, these studies are being superseded by in vitro studies. Instead, the time taken to produce 90% inhibition of nerve-mediated twitches (i.e. t90) in skeletal muscle preparations can be determined".
Sources: en.wikipedia.org
==== Nations ==== Bahrain: Bahrain called for a lasting solution that will prevent Iran from getting nuclear weapons or from doing things that could destabilize the region. France: President Emmanuel Macron said that he remained concerned about the "critical" situation in Lebanon, after Israel continued its strikes and occupation of southern Lebanon after the ceasefire, stating that this "cannot be a long-term solution." France also looked forward to securing shipping through the Strait of Hormuz. Germany: Germany urged Iran to respect the ceasefire and to allow ships to cross the Strait of Hormuz safely and freely. They also urged Iran to take advantage of the opportunity for negotiations. India: The Indian Ministry for External Affairs welcomed the US-Iran ceasefire agreement and called for an early end to the conflict for "unimpeded" trade flow through the Strait of Hormuz. Iraq: The Iraqi oil ministry said on 9 April that no Iraqi ships had crossed the Strait since the ceasefire came into effect. Kuwait: Kuwait's foreign ministry urged Iran and its "proxies, including factions, militias, and armed groups loyal to it" to cease all hostilities against Gulf Arab states. Qatar: Qatar's foreign ministry considered the ceasefire "an initial step toward de-escalation" and hoped Iran would "cease all hostile acts and practices that undermine regional stability." Russia: Russia welcomed the ceasefire and expressed hope that the United States would be able to resume peace negotiations in the Russo-Ukrainian war.
Square pyramidal for five-coordination Capped octahedral or capped trigonal prismatic for seven-coordination Dodecahedral or bicapped trigonal prismatic for eight-coordination Capped square antiprismatic for nine-coordination To distinguish between the alternative coordinations for five-coordinated complexes, the τ geometry index was invented by Addison et al. This index depends on angles by the coordination center and changes between 0 for the square pyramidal to 1 for trigonal bipyramidal structures, allowing to classify the cases in between. This system was later extended to four-coordinated complexes by Houser et al. and also Okuniewski et al. In systems with low d electron count, due to special electronic effects such as (second-order) Jahn–Teller stabilization, certain geometries (in which the coordination atoms do not follow a points-on-a-sphere pattern) are stabilized relative to the other possibilities, e.g. for some compounds the trigonal prismatic geometry is stabilized relative to octahedral structures for six-coordination.
Corey Taylor − vocals, guitar on track 17, additional guitar on tracks 4, 8 and 12 James Root − guitar (on all tracks except 18), drums on track 15 Josh Rand − guitar (on all tracks except 18) Shawn Economaki − bass (on all tracks except 17 and 18) Roy Mayorga − drums (on all tracks except 1, 15, 17 and 18) Additional personnel
This tornado was part of a small outbreak that affected Europe that day, which produced a total of seven tornadoes. In Poland, one person was injured by an F2 tornado that impacted the towns of Librantowa and Koniuszowa, damaging numerous structures, 15 of which had their roofs torn off. Numerous reports of damaging straight-line winds and large, destructive hail were received as well. Weather of 2021 List of tornadoes rated on the International Fujita scale List of European tornadoes and tornado outbreaks List of F4 and EF4 tornadoes List of F4 and EF4 tornadoes (2020–present) October 2022 European tornado outbreak – An EF3 tornado struck Bihucourt F4 Tornado Hits Hodonín, Czechia - Jun. 24, 2021 tornádo v Hodoníně F4 Tornado Hits Hodonín, Czechia - Jun. 24, 2021 tornádo v Hodoníně (Part 2) Inside of an F4 tornado (full version)
=== Beta counting === Libby's first detector was a Geiger counter of his own design. He converted the carbon in his sample to lamp black (soot) and coated the inner surface of a cylinder with it. This cylinder was inserted into the counter in such a way that the counting wire was inside the sample cylinder, in order that there should be no material between the sample and the wire. Any interposing material would have interfered with the detection of radioactivity, since the beta particles emitted by decaying 14C are so weak that half are stopped by a 0.01 mm thickness of aluminium. Libby's method was soon superseded by gas proportional counters, which were less affected by bomb carbon (the additional 14C created by nuclear weapons testing). These counters record bursts of ionization caused by the beta particles emitted by the decaying 14C atoms; the bursts are proportional to the energy of the particle, so other sources of ionization, such as background radiation, can be identified and ignored. The counters are surrounded by lead or steel shielding, to eliminate background radiation and to reduce the incidence of cosmic rays. In addition, anticoincidence detectors are used; these record events outside the counter and any event recorded simultaneously both inside and outside the counter is regarded as an extraneous event and ignored.
Sources: en.wikipedia.org
The mass difference from the linker is large enough for routine detection by mass spectrometry. The unconjugated form gives a single sharp signal at its expected weight. Material that has already reacted with albumin shows a much higher mass and a broadened chromatographic peak.
Yes. Degradation proceeds faster once the powder is dissolved, especially at room temperature or after multiple freeze and thaw cycles. Working solutions are often aliquoted to avoid repeated handling. Lyophilized powder held cold and dry retains its properties far longer.
Truncated sequences, oxidized residues and aggregated forms can all elute near the main peak. Reversed phase chromatography resolves many of these species, so the number of peaks is a useful indicator of synthesis quality. A single peak does not by itself prove correct sequence, which is why mass confirmation is paired with it.
The powder is normally held at minus twenty degrees Celsius or below. Light and moisture exposure should be minimized. Repeated warming and cooling cycles are avoided.