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Guanine

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guanine (gwä`nēn), organic base of the purine purine, type of organic base found in the nucleotides and nucleic acids of plant and animal tissue. The German chemist Emil Fischer did much of the basic work on purines and introduced the term into the chemical literature in the early 20th cent.
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 family. It was reported (1846) to be in the guano guano , dried excrement of sea birds and bats found principally on the coastal islands of Peru, Africa, Chile, and the West Indies. It contains about 6% phosphorus, 9% nitrogen, 2% potassium, and moisture.
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 of birds; later (1879–84) it was established as one of the major constituents of nucleic acids nucleic 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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. The accepted structure of the guanine molecule was proposed in 1875, and the compound was first synthesized in 1900. When combined with the sugar ribose in a glycosidic linkage, guanine forms a derivative called guanosine (a nucleoside), which in turn can be phosphorylated with from one to three phosphoric acid groups, yielding the three nucleotides nucleotide , organic substance that serves as a monomer in forming nucleic acids. Nucleotides consist of either a purine or a pyrimidine base, a ribose or deoxyribose, and a phosphate group.
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 GMP (guanosine monophosphate), GDP (guanosine diphosphate), and GTP (guanosine triphosphate). Analogous nucleosides and nucleotides are formed from guanine and deoxyribose. The nucleotide derivatives of guanine perform important functions in cellular metabolism. GTP acts as a coenzyme coenzyme , 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
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 in carbohydrate metabolism and in the biosynthesis of proteins; it can readily donate one of its phosphate groups to adenosine diphosphate (ADP) to form adenosine triphosphate adenosine triphosphate (ATP) , organic compound composed of adenine, the sugar ribose, and three phosphate groups. ATP serves as the major energy source within the cell to drive a number of biological processes such as photosynthesis, muscle contraction, and the
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 (ATP), an extremely important intermediate in the transfer of chemical energy in living systems. GTP is the source of the guanosine found in RNA and deoxyguanosine triphosphate (dGTP) is the source of the deoxyguanosine in DNA, and thus guanine is intimately involved in the preservation and transfer of genetic information. Guanine is said to account for the iridescence of fish scales and the white, shiny appearance of the skin of many amphibians and reptiles.

guanine

Organic compound of the purine family, often called a base, consisting of two rings, each containing both nitrogen and carbon atoms, and an amino group. It occurs in combined form in many important biological molecules, particularly nucleic acids, and free or combined in various natural sources, including guano, sugar beets, yeast, and fish scales. In DNA its complementary base is cytosine. It or its corresponding nucleoside or nucleotide may be prepared from nucleic acids by selective techniques of hydrolysis.


guanine [′gwän‚ēn]
(biochemistry)
C5H5ON5A purine base; occurs naturally as a fundamental component of nucleic acids.

Guanine 

2-amino-6-oxypurine. a purine base, widely distributed in animal and plant cells (it is a constituent of nucleic acids and is present in a free state).

It is the main component of the excrements of spiders and birds and was discovered in guano (hence the name). A considerable amount of guanine is present in the scales and skin of fish, reptiles, and amphibians. The calcium compound of guanine gives fish scales their characteristic shine. In mammal organisms, guanine is transformed into xanthine under the action of the enzyme guanase.



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Guanine is known to be particularly sensitive to oxidative damage, according to background information in the research article.
To investigate, Levy-Lior and her colleagues extracted guanine crystals from the skin of the Japanese koi fish and redeye tetra and analyzed them with X-ray diffraction and an electron microscope.
The bird poo is said to be packed with the enzyme guanine, which is claimed to repair "tortured", dull skin.
 
 
 
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