The short version of Guanidino group fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-03. Anything still debated is marked as such rather than presented as settled.
Solid creatine monohydrate is relatively stable when kept dry and sealed, but heat and moisture accelerate its conversion to creatinine. This degradation involves intramolecular cyclization, a process that removes water and forms a less useful compound for phosphocreatine metabolism. Powder stored under cool, dry conditions can remain within specification for extended periods, though exact shelf life depends on packaging, humidity, and initial purity. Aqueous solutions degrade faster than dry powder, with pH and temperature influencing the rate. Because degradation is gradual, analytical testing is used to confirm potency at manufacture and during stability studies.
Quality control for creatine monohydrate typically combines identity, assay, and impurity tests. High-performance liquid chromatography with ultraviolet detection is common for separating creatine from creatinine and related substances. Nuclear magnetic resonance and infrared spectroscopy can confirm molecular structure, while titration may assess acid-base content. Moisture content, heavy metals, residual solvents, and microbial limits are checked according to applicable standards. These tests help distinguish compliant material from powders that have degraded, been diluted, or contain manufacturing residues.
Creatine monohydrate is a crystalline compound formed when one molecule of creatine binds with one molecule of water. Creatine itself is a nitrogen-containing organic acid involved in cellular energy transfer, particularly in muscle and nerve tissue. The monohydrate form is the most common solid form used in research and commercial products because it is relatively stable and easy to handle. Its molecular formula is C4H9N3O2·H2O, and its molar mass is about 149.15 grams per mole.
In the human body, creatine is synthesized mainly in the liver and kidneys from the amino acids glycine, arginine, and methionine. Dietary sources include meat, fish, and other animal tissues, which supply preformed creatine. Because plant foods contain little or no creatine, dietary intake varies widely among populations. The compound is stored largely in skeletal muscle, where it is converted to phosphocreatine and used to regenerate adenosine triphosphate during short bursts of activity.
Creatine monohydrate is one of several solid forms of creatine described in the literature. Other forms include anhydrous creatine, creatine hydrochloride, and creatine ethyl ester, each with different solubility and stability characteristics. The monohydrate is distinct from creatinine, a spontaneous breakdown compound that forms when creatine loses water and cyclizes. Commercial descriptions sometimes use synonyms such as methylguanidoacetic acid or N-(aminoiminomethyl)-N-methylglycine, which refer to the same base molecule. These names appear in chemical databases and product labels.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15–25 °C | Cool, dry, sealed |
| Relative humidity | Below 60% | Moisture promotes caking and degradation |
| Degradation product | Creatinine | Forms by cyclization, especially in solution |
| Assay method | HPLC with UV detection | Often paired with identity tests |
| Aqueous stability | Hours to days at room temperature | Depends on pH, temperature, concentration |
==== Bicycle and pedestrian ==== The Maine-to-Florida U.S. Bicycle Route#1 routes through suburban Raleigh, along with N.C. Bicycle Route #2, the "Mountains To Sea" route. As of September 2010, maps and signage for both US Bike Route No. 1 and NC Bike Route No. 2 are out-of-date for the Raleigh area. N.C. Bicycle Route #5 is routed nearby, connecting Apex to Wilmington and closely paralleling the NCBC Randonneurs 600-kilometer brevet route. Most public buses are equipped with bicycle racks, and some roads have dedicated bicycle-only lanes. Bicyclists and pedestrians also may use Raleigh's extensive greenway system, with paths and trails located throughout the city. In May 2011, Raleigh was designated a Bicycle Friendly Community by the League of American Bicyclists at the Bronze level. In 2002, the "Walk [Your City]" initiative was started in the city which provides a tool kit for neighborhood organizations to post signs giving a distance by bike or foot, with directions in scannable QR code. The movement has spread to more than 400 communities in 55 countries.
==== Chinese, Korean, and Japanese-language ==== A 2010 systematic review of the Chinese-language literature found numerous acupuncture-related adverse events, including pneumothorax, fainting, subarachnoid hemorrhage, and infection as the most frequent, and cardiovascular injuries, subarachnoid hemorrhage, pneumothorax, and recurrent cerebral hemorrhage as the most serious, most of which were due to improper technique. Between 1980 and 2009, the Chinese-language literature reported 479 adverse events. Prospective surveys show that mild, transient acupuncture-associated adverse events ranged from 6.71% to 15%. In a study with 190,924 patients, the prevalence of serious adverse events was roughly 0.024%. Another study showed a rate of adverse events requiring specific treatment of 2.2%, 4,963 incidences among 229,230 patients. Infections, mainly hepatitis, after acupuncture are reported often in English-language research, though are rarely reported in Chinese-language research, making it plausible that acupuncture-associated infections have been underreported in China. Infections were mostly caused by poor sterilization of acupuncture needles.
Denaturing High Performance Liquid Chromatography (DHPLC) is a method of chromatography for the detection of base substitutions, small deletions or insertions in the DNA. Due to its speed and high resolution, this method is particularly useful for finding polymorphisms in DNA. In practice, the analysis begins with a standard polymerase chain reaction (PCR) in order to amplify the fragment of interest. If the amplified region that exhibits the polymorphism(s) is heterozygous, two kinds of fragments corresponding to the allele and the wild polymorphic allele will be present in the PCR product. This first step is followed by a step of denaturation–renaturation to create hetero- and homoduplexes from the two allele populations in the PCR. To find a homozygous polymorphism, proceed in the same way by premixing a DNA wild population to a population of polymorphic DNA to obtain heteroduplexes after the denaturation–renaturation step. Heteroduplexes are actually double strands of DNA containing a strand from the wild-type allele and a sprig from the polymorphic allele. The formation of such DNA fragments then causes the appearance of a "mismatch" or bad pairing where the polymorphism is located. These "mismatches" in the heteroduplex are the basis for the polymorphism detection by DHPLC. Heteroduplexes are thermally less stable than their corresponding homoduplexes, and the single DNA strands will therefore be disconnected by chromatography when subjected to a sufficiently high temperature.
Sources: en.wikipedia.org
== Superior == The superior tarsus (tarsus superior; superior tarsal plate), the larger, is of a semilunar form, about 10 mm (0.4 in) in breadth at the center, and gradually narrowing toward its extremities. It is adjoined by the superior tarsal muscle. To the anterior surface of this plate the aponeurosis of the levator palpebrae superioris is attached.
=== Degradation === Histidine can be metabolized into glutamate, which is readily metabolized into AKG (alpha-ketoglutarate), making histidine one of the amino acids whose metabolites can become citric acid cycle intermediates. The process requires several steps. In prokaryotes, histidine first undergoes deamination, the removal of its amino group by the emzyme histidase. This step produces ammonia and urocanic acid (urocanate). The enzyme urocanase then converts urocanic acid into imidazolonepropionate (4-imidazolone-5-propionate). The enzyme imidazolonepropionase then converts imidazolonepropionate into formiminoglutamate (FIGLU). The enzyme formimidoyltransferase cyclodeaminase removes the formimino group (which is transferred to tetrahydrofolate), leaving behind a glutamate molecule. Glutamate can then be deaminated by glutamate dehydrogenase or transaminated to form α-ketoglutarate.
== Conclusion == Owing to its non-specific cytotoxicity, instability under ambient conditions, and relative expense of isolation and manufacture, kedarcidin chromophore has not been investigated rigorously as a therapeutic candidate. However, the recent scientific advances discussed above have served to diminish this last hurdle, as fully synthetic and biosynthetic routes toward scalable kedarcidin production are now within reach. Moreover, with the rising popularity of antibody-drug conjugate therapies, toxicity liabilities may be mitigated through targeted delivery of this potent cytotoxin, potentially enabling efficient therapies that use minimal quantities of this complex material. The recent development of inotuzumab ozogamicin, a calicheamicin-based antibody-drug conjugate for the treatment of non-Hodgkin lymphoma, reinforces the potential of enediynes to find critical use in the treatment of human disease. Thus, the biological potential and complex molecular architecture of kedarcidin may likely inspire further scientific inquiry into this substance, and possibly deliver new ordnance in the war against cancer.
== Aliphatic formylation == Hydroformylation of alkenes is the most important method for obtaining aliphatic formyls (i.e., aldehydes). The reaction is largely restricted to industrial settings. Several specialty methods exist for laboratory-scale synthesis, including the Sommelet reaction, Bouveault aldehyde synthesis or Bodroux–Chichibabin aldehyde synthesis.
Sources: en.wikipedia.org
Keep it in a sealed container in a cool, dry place away from direct heat and moisture. Dry powder is more stable than prepared solutions.
It can cyclize into creatinine, particularly in water or under heat. Creatinine does not support phosphocreatine energy buffering in the same way.
Laboratories commonly use chromatographic methods such as HPLC, along with spectroscopy and titration, to confirm identity and quantity. Moisture, elemental impurities, and microbial limits may also be tested.
Creatine monohydrate is the hydrated solid form of creatine, a nitrogen-containing compound involved in cellular energy metabolism. It consists of one creatine molecule associated with one water molecule in a crystal lattice.