metabolite

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metabolite,

organic compound that is a starting material in, an intermediate in, or an end product of metabolismmetabolism,
sum of all biochemical processes involved in life. Two subcategories of metabolism are anabolism, the building up of complex organic molecules from simpler precursors, and catabolism, the breakdown of complex substances into simpler molecules, often accompanied by
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. Starting materials are substances, usually small and of simple structure, absorbed by the organism as food. These include the vitamins and essential amino acids. They can be used to construct more complex molecules, or they can be broken down into simpler ones. Intermediary metabolites are by far the most common; they may be synthesized from other metabolites, perhaps used to make more complex substances, or broken down into simpler compounds, often with the release of chemical energy. For example, glucose, perhaps the single most important metabolite, can be synthesized in a process called gluconeogenesis, can be polymerized to form starch or glycogen, and can be broken down during glycolysis in order to obtain chemical energy. End products of metabolism are the final result of the breakdown of other metabolites and are excreted from the organism without further change; they usually cannot be used to synthesize other metabolites. Urea, for example, is an end product of protein degradation in man, the other primates, and the Dalmatian dog. Carbon dioxide is usually thought of as an end product of carbohydrate, protein, and fat degradation in aerobic organisms, although technically, carbon dioxide, as carbonic acid, can participate in the biosynthesis of some substances, particularly in plants. Complex substances such as proteins, although end products of a synthetic process, can almost always be broken down again and are usually not considered to be true end products of metabolism. A compound that closely resembles a metabolite in molecular structure but is metabolically inactive is called an antimetabolite; such a substance is often used as a drug in the treatment of malignant disease. When introduced into the body, it is mistaken by the cell for the metabolite it simulates, thus preventing the cell from using the genuine substance necessary to its life and growth. It is difficult to design molecules so that they will be metabolic poisons for malignant cells and not for normal cells as well. Folic acid (see coenzymecoenzyme
, any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a particular enzyme or exist freely in solution, but in either case it participates intimately in
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) antagonists such as aminopterin and methotrexate are used in the treatment of leukemiasleukemia
, cancerous disorder of the blood-forming tissues (bone marrow, lymphatics, liver, spleen) characterized by excessive production of immature or mature leukocytes (white blood cells; see blood) and consequently a crowding-out of red blood cells and platelets.
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 and other neoplastic diseases. The purine antagonist mercaptopurine is also used for the treatment of acute leukemia, while azathioprine (Imuran) is used to prevent the rejection of transplanted organs. Pyrimidine antagonists used in cancer chemotherapy include fluorouracil and fluorodeoxyuridine. Most of the agents are designed to halt cell division in rapidly dividing malignant cells by the disruption of the metabolism of purines and pyrimidines, two classes of compounds necessary for nucleic acidnucleic acid,
any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis.
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 synthesis and hence necessary for cell division.

metabolite

[mə′tab·ə‚līt]
(biochemistry)
A product of intermediary metabolism.
References in periodicals archive ?
Since the breakdown product for lindane was not found, this could represent recent exposure.
Belonging to this OCP group is DDE, a breakdown product of DDT, which was used as an agricultural insecticide until it was banned in the UK in the 1970s.
These gases are the hydrocarbon breakdown product of organic binders - especially urethane-based cold-set and shell mold systems - released during pouring as the metal comes in contact with the mold or core surface.
The team found lower amounts of serotonin and a key serotonin breakdown product in the shift workers.
(Cotinine is a breakdown product of nicotine found in blood.) The study took into account many other factors including age, sex, region, dental care, socioeconomic and nutritional status, and blood lead levels.
The research focused on the complex relationship between amyloid precursor protein (APP) and its breakdown product amyloid, along with the zinc and iron.
Smokers' cotinine (a tobacco breakdown product) and carbon monoxide blood levels are the same whether they use low-tar or regular-tar cigarettes.
The weak environmental estrogens included p-nonylphenol (a breakdown product of alkylphenol ethoxylates, which are used in various products such as washing and cleaning agents, emulsifiers, wetting agents, and foaming and foam-reducing agents) and the organochlorine pesticides methoxychlor and endosulfan.
Cotinine is a metabolic breakdown product of nicotine that is found in urine and is easily measured.
Tests at the Centers for Disease Control and Prevention in Atlanta turned up a metabolic breakdown product of DEHP in nearly every sample, the team reports in an upcoming Environmental Health Perspectives.
Bilirubin, a breakdown product of red blood cells, accumulates in the skin, resulting in the yellow or jaundice appearance of these babies.
Blood concentrations of cotinine, a breakdown product of nicotine, have dropped by 68 to 75 percent in various age groups since a previous CDC study examined data covering 1988 to 1991.