Purine


Purine

chembox
ImageFile=Purine chemical structure.pngImageSize= 345px
ImageFile2=
IUPACName=7H-purine
OtherNames=
Section1= Chembox Identifiers
CASNo=120-73-0
PubChem=1044
ChemSpiderID = 1015
SMILES=C1=C2C(=NC=N1)N=CN2
MeSHName=Purine

Section2= Chembox Properties
Formula=C5H4N4
MolarMass=120.112
Appearance=
Density=
MeltingPt=214 °C
BoilingPt=
Solubility=

Section3= Chembox Hazards
MainHazards=
FlashPt=
Autoignition=

Purine (1) is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines and pyrimidines make up the two groups of nitrogenous bases. These bases make up a crucial part of both deoxyribonucleotides and ribonucleotides, and the basis for the universal genetic code.

The general term purines also refers to substituted purines and their tautomers.

The purine is the most widely distributed nitrogen-containing heterocycle in nature. [Rosemeyer, H. "Chemistry & Biodiversity" 2004, "1", 361.]

Notable purines

The quantity of naturally occurring purines produced on earth is enormous, as 50 % of the bases in nucleic acids, adenine (2) and guanine (3), are purines. In DNA, these bases form hydrogen bonds with their complementary pyrimidines thymine and cytosine. This is called complementary base pairing. In RNA, the complement of adenine is uracil (U) instead of thymine.

Other notable purines are hypoxanthine (4), xanthine (5), theobromine (6), caffeine (7), uric acid (8) and isoguanine (9).

Functions

Aside from DNA and RNA, purines are biochemically significant components in a number of other important biomolecules, such as ATP, GTP, cyclic AMP, NADH, and coenzyme A. Purine (1) itself, has not been found in nature, but it can be produced by organic synthesis.

They may also function directly as neurotransmitters, acting upon purinergic receptors. Adenosine activates adenosine receptors.

History

The name 'purine' ("purum uricum") was coined by the German chemist Emil Fischer in 1884. He synthesized it for the first time in 1899. [Fischer, E. "Berichte der Deutschen Chemischen Gesellschaft" 1899, "32", 2550.] The starting material for the reaction sequence was uric acid (8), which had been isolated from kidney stones by Scheele in 1776. [Scheele, V. Q. Examen Chemicum Calculi Urinari, "Opuscula", 1776, "2", 73.] Uric acid (8) was reacted with PCl5 to give 2,6,8-trichloropurine (10), which was converted with HI and PH4I to give 2,6-diiodopurine (11). This latter product was reduced to purine (1) using zinc-dust.

Metabolism

Many organisms have metabolic pathways to synthesize and break down purines.

Purines are biologically synthesized as nucleosides (bases attached to ribose).

Food sources

Purines are found in high concentration in meat and meat products, especially internal organs such as liver and kidney. Plant based diet is generally low in purines [http://www.dietaryfiberfood.com/purine-food.php] .

Examples of high purine sources include: sweetbreads, anchovies, sardines, liver, beef, kidneys, brains, meat extracts, herring, mackerel, scallops, game meats, and gravy.

A moderate amount of purine is also contained in beef, pork, poultry, fish and seafood, asparagus, cauliflower, spinach, mushrooms, green peas, lentils, dried peas, beans, oatmeal, wheat bran and wheat germ. [ [http://www.healthcastle.com/gout.shtml Gout Diet: Limit High Purine Foods ] ]

Moderate intake of purine-containing food is not associated with an increased risk of gout. [ [http://content.nejm.org/cgi/content/abstract/350/11/1093 NEJM - Purine-Rich Foods, Dairy and Protein Intake, and the Risk of Gout in Men ] ]

Laboratory synthesis

In addition to in vivo synthesis of purines in purine metabolism, purine can also be created artificially.

Purine (1) is obtained in good yield when formamide is heated in an open vessel at 170 oC for 28 hours.Yamada, H.; Okamoto, T. "Chemical & Pharmaceutical Bulletin", 1972, "20", 623.]

Procedure:Formamide (45 gram) was heated in an open vessel with a condenser for 28 hours in an oil bath at 170-190 oC. After removing excess formamide (32.1 gram) by vacuum distillation, the residue was refluxed with methanol. The methanol solvent was filtered, the solvent removed from the filtrate by vacuum distillation, and almost pure purine obtained; yield 4.93 gram (71 % yield from formamide consumed). Crystallization from acetone afforded purine as colorless crystals; melting point 218 oC.

Oro, Orgel and co-workers have shown that four molecules of HCN tetramerize to form diaminomaleodinitrile (12), which can be converted into almost all important natural occurring purines. [Sanchez, R. A.; Ferris, J. P.; Orgel, L. E. "Journal of Molecular Biology", 1967, "30", 223.] [Ferris, J. P.; Orgel, L. E. "Journal of the American Chemical Society", 1966, "88", 1074.] [Ferris, J. P.; Kuder, J. E.; Catalano, O. W. "Science", 1969, "166", 765.] [Oro, J.; Kamat, J. S. "Nature", 1961, "190", 442.] [Houben-Weyl, Vol . E5, p. 1547]

The Traube purine synthesis (1900) is a classic reaction (named after Wilhelm Traube) between an amine substutited pyrimidine and formic acid ["Organic Syntheses Based on Name Reactions", Alfred Hassner, C. Stumer ISBN 008043259X 2002]

References

See also

* Simple aromatic rings
* Pyrimidine

External links

* [http://www.compchemwiki.org/index.php?title=Purine Computational Chemistry Wiki]
* [http://www.dietaryfiberfood.com/purine-food.php Purine Content in Food]


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Look at other dictionaries:

  • Purine — Structure et représentation de la 9H Purine ou (3H imidazo)[4,5 d]pyrimidine Général …   Wikipédia en Français

  • purine — [ pyrin ] n. f. • 1904; all. Purin, dér. sav. du rad. du lat. purus « pur » et de urique ♦ Biochim. Substance azotée basique dont la structure comporte deux chaînes fermées (l une à 5, l autre à 6 atomes). ● purine nom féminin Composé… …   Encyclopédie Universelle

  • purine — [pyoor′ēn΄, pyoor′in] n. [Ger purin < L purus, pure + ModL uricum, uric acid + in, INE3] 1. a colorless, crystalline organic compound, C5H4N4, the parent substance of the uric acid group of compounds 2. any of several basic substances produced …   English World dictionary

  • purine — purine. См. пурин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • purine — 1898, from Ger. purin, said to be from L. purum “pure” (see PURE (Cf. pure)) + Mod.L. uricum “uric acid” + chemical suffix INE (Cf. ine) (2) …   Etymology dictionary

  • Purine — Strukturformel Allgemeines Name Purin Andere Namen 3,5,7 Triazaindol 7H Imidazo(4,5 d)pyrimidin …   Deutsch Wikipedia

  • purine — /pyoor een, in/, n. Chem., Biochem. 1. a white, crystalline compound, C5H4N4, from which is derived a group of compounds including uric acid, xanthine, and caffeine. 2. one of several purine derivatives, esp. the bases adenine and guanine, which… …   Universalium

  • Purine — One of the two classes of bases in DNA and RNA. The purine bases are guanine (G) and adenine (A). Uric acid, the offending substance in gout, is a purine end product. * * * The parent substance of adenine, guanine, and other naturally occurring p …   Medical dictionary

  • purine — noun Etymology: German Purin, from Latin purus pure + New Latin uricus uric (from English uric) + German in 2 ine Date: 1898 1. a crystalline base C5H4N4 that is the parent of compounds of the uric acid group 2. a derivative of purine; especially …   New Collegiate Dictionary

  • purine — (pu rin) A basic, heterocyclic, nitrogen containing molecule with two joined rings that occurs in nucleic acids and other cell constituents; most purines are oxy or amino derivatives of the purine skeleton. The most important purines are adenine… …   Dictionary of microbiology


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