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Purine (1) is a heterocyclic
Heterocyclic compound

Heterocyclic compounds are organic compounds containing at least one atom of carbon, and at least one element other than carbon, such as sulfur, oxygen or nitrogen within a ring structure....
 aromatic organic compound
Organic compound

An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered Inorganic compound....
, consisting of a pyrimidine
Pyrimidine

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring....
 ring fused to an imidazole
Imidazole

Imidazole is a organic compound with the formula C3H4N2. This aromatic heterocyclic is classified as an alkaloid....
 ring. Purines, including substituted purines and their tautomer
Tautomer

Tautomers are isomers of organic compounds that readily interconvert by a chemical reaction called tautomerization. Commonly this reaction results in the formal migration of a hydrogen atom or proton, accompanied by a switch of a single bond and adjacent double bond....
s, are the most widely distributed kind of nitrogen-containing heterocycle in nature.

Purines and pyrimidines make up the two groups of nitrogenous bases, including the two groups of nucleotide bases. Two of the four deoxyribonucleotide
Deoxyribonucleotide

A deoxyribonucleotide is the monomer, or single unit, of DNA, or deoxyribonucleic acid. Each deoxyribonucleotide comprises three parts: A nitrogenous base, a deoxyribose sugar, and one or more phosphate groups....
s and two of the four ribonucleotide
Ribonucleotide

A ribonucleotide is a nucleotide in which a purine or pyrimidine base is linked to a ribose molecule. The base may be adenine , guanine , cytosine , or uracil ....
s, the respective building blocks of DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
 and RNA
RNA

Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate....
, are purines.

quantity of naturally occurring purines produced on earth is enormous, as 50 % of the bases in nucleic acid
Nucleic acid

A nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry these molecules carry genetic information or form structures within Cell ....
s, adenine
Adenine

Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactor s nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and Protein biosynthesis, as a chemical component of DNA and RNA....
 (2) and guanine
Guanine

Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, thymine, and uracil. In DNA, guanine is paired with cytosine....
 (3), are purines.






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Purine (1) is a heterocyclic
Heterocyclic compound

Heterocyclic compounds are organic compounds containing at least one atom of carbon, and at least one element other than carbon, such as sulfur, oxygen or nitrogen within a ring structure....
 aromatic organic compound
Organic compound

An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered Inorganic compound....
, consisting of a pyrimidine
Pyrimidine

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring....
 ring fused to an imidazole
Imidazole

Imidazole is a organic compound with the formula C3H4N2. This aromatic heterocyclic is classified as an alkaloid....
 ring. Purines, including substituted purines and their tautomer
Tautomer

Tautomers are isomers of organic compounds that readily interconvert by a chemical reaction called tautomerization. Commonly this reaction results in the formal migration of a hydrogen atom or proton, accompanied by a switch of a single bond and adjacent double bond....
s, are the most widely distributed kind of nitrogen-containing heterocycle in nature.

Purines and pyrimidines make up the two groups of nitrogenous bases, including the two groups of nucleotide bases. Two of the four deoxyribonucleotide
Deoxyribonucleotide

A deoxyribonucleotide is the monomer, or single unit, of DNA, or deoxyribonucleic acid. Each deoxyribonucleotide comprises three parts: A nitrogenous base, a deoxyribose sugar, and one or more phosphate groups....
s and two of the four ribonucleotide
Ribonucleotide

A ribonucleotide is a nucleotide in which a purine or pyrimidine base is linked to a ribose molecule. The base may be adenine , guanine , cytosine , or uracil ....
s, the respective building blocks of DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
 and RNA
RNA

Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate....
, are purines.

Notable purines

The quantity of naturally occurring purines produced on earth is enormous, as 50 % of the bases in nucleic acid
Nucleic acid

A nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry these molecules carry genetic information or form structures within Cell ....
s, adenine
Adenine

Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactor s nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and Protein biosynthesis, as a chemical component of DNA and RNA....
 (2) and guanine
Guanine

Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, thymine, and uracil. In DNA, guanine is paired with cytosine....
 (3), are purines. In DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
, these bases form hydrogen bond
Hydrogen bond

A hydrogen bond is the attractive force between one electronegative atom and a hydrogen covalently bonded to another electronegative atom. It results from a dipole-dipole force with a hydrogen atom bonded to nitrogen, oxygen or fluorine ....
s with their complementary
Complementarity (molecular biology)

In molecular biology, complementarity is a property of double-stranded nucleic acids such as DNA and RNA as well as DNA:RNA duplexes. Each strand is complementary to the other in that the base pairs between them are non-covalent bond connected via two or three hydrogen bonds....
 pyrimidine
Pyrimidine

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring....
s thymine
Thymine

Thymine is one of the four bases in the nucleic acid of DNA that make up the letters GCAT. The others are adenine, guanine, and cytosine. Thymine always pairs with adenine....
 and cytosine
Cytosine

Cytosine is one of the five main bases found in DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached ....
 respectively. This is called complementary base pairing. In RNA
RNA

Ribonucleic acid is a type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nucleobase, a ribose sugar, and a phosphate....
, the complement of adenine is uracil
Uracil

Uracil is a common and naturally occurring pyrimidine derivative. Originally discovered in 1900, it was isolated by hydrolysis of yeast nuclein that was found in bovine thymus and spleen, herring, sperm, and wheat germ....
 (U) instead of thymine.

Other notable purines are hypoxanthine
Hypoxanthine

Hypoxanthine is a naturally occurring purine derivative. It is occasionally found as a constituent of nucleic acids where it is present in the anticodon of tRNA in the form of its nucleoside inosine....
 (4), xanthine
Xanthine

Xanthine , , is a purine base found in most body tissues and fluids and in other organisms. A number of mild stimulants are derived from xanthine, including caffeine and theobromine....
 (5), theobromine
Theobromine

Theobromine, also known as xantheose, is a bitter alkaloid of the cacao plant, found in chocolate, as well as in a number of chocolate-free foods made from theobromine sources including the leaves of the tea plant, the kola or cola nut, and acai berries....
 (6), caffeine
Caffeine

Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a psychoactive stimulant drug and a mild diuretic. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819....
 (7), uric acid
Uric acid

Uric acid is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3....
 (8) and isoguanine
Isoguanine

Isoguanine or 2-hydroxyladenine is a purine base that is an isomer of guanine. It is a product of oxidative damage to DNA and has been shown to cause mutation....
 (9).

Functions

Aside from DNA and RNA, purines are biochemically significant components in a number of other important biomolecules, such as ATP
Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
, GTP
Guanosine triphosphate

Guanosine-5'-triphosphate is a purine nucleotide. One role is as substrate for the synthesis of RNA during transcription . Its structure is similar to that of the guanine nucleoside, the only difference being that there are three phosphate groups attached to the 5' carbon....
, cyclic AMP, NADH, and coenzyme A
Coenzyme A

Coenzyme A is a coenzyme, notable for its role in the Fatty acid metabolism#Synthesis and Fatty acid metabolism#.CE.B2-Oxidation of fatty acids, and the oxidation of pyruvic acid in the citric acid cycle....
. Purine (1) itself, has not been found in nature, but it can be produced by organic synthesis
Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic_chemistry molecules can often contain a higher level of complexity compared to purely Inorganic_chemistry compounds, so the synthesis of organic compounds has developed into one of the most im...
.

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

The adenosine receptors are a class of purinergic receptors, G-protein coupled receptors with adenosine as endogenous ligand.In humans, there are four adenosine receptors....
s.

History


The name 'purine' (purum uricum) was coined by the German
Germany

Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, and the Netherlands....
 chemist
Chemist

A chemist is a scientist trained in the science of chemistry. Chemists study the composition of matter and its properties such as density, acidity, size and shape....
 Emil Fischer
Emil Fischer

Emil Fischer may refer to:* Emil Fischer , famous German dramatic basso* Franz Joseph Emil Fischer , German chemist* Hermann Emil Fischer , German chemist...
 in 1884. He synthesized it for the first time in 1899. The starting material for the reaction sequence was uric acid (8), which had been isolated from kidney stones by Scheele in 1776. Uric acid (8) was reacted with PCl5 to give 2,6,8-trichloropurine (10), which was converted with HI and PH4I
Phosphonium salt

A phosphonium salt is a salt containing the phosphonium ion such as phosphonium iodide . More commonly, phosphonium refer to an organic derivative such as tetraphenylphosphonium chloride, 4P+ Cl- and tetramethylphosphonium iodide, [P4]+I− to give 2,6-diiodopurine (11). This latter product was reduced to purine (1) using zinc-dust.

Metabolism

Many organisms have metabolic pathway
Metabolic pathway

In biochemistry, a metabolic pathway is a series of chemistry reactions occurring within a cell . In each pathway, a principal chemical is modified by chemical reactions....
s to synthesize and break down purines.

Purines are biologically synthesized as nucleoside
Nucleoside

Nucleosides are glycosylamines consisting of a nucleobase bound to a ribose or deoxyribose sugar. Examples of these include cytidine, uridine, adenosine, guanosine, thymidine and inosine....
s (bases attached to ribose
Ribose

Ribose, primarily occurring as D-ribose, is an organic compound that occurs widely in nature. It is an aldopentose, that is a monosaccharide containing five carbon atoms that, in its acyclic form, has an aldehyde functional group at one end....
).

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 .

Examples of high purine sources include: sweetbread
Sweetbread

File:Sweetbreads.jpgSweetbreads are the thymuss and pancreas glands of lamb and mutton, beef, or pork. There are two different connected parts to the thymus gland, both set in the neck....
s, anchovies, sardine
Sardine

Sardines, or pilchards, are a group of several types of small, oily fish related to herrings, family Clupeidae. Sardines were named after the island of Sardinia, where they were once in abundance....
s, liver, beef kidneys, brains, meat extract
Meat extract

Meat extract is highly concentrated meat stock , usually made from beef. It is used to add meat flavor in cooking, and to make broth for drinking....
s (e.g Oxo, Bovril), herring, mackerel
Mackerel

Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They occur in all tropical and temperate seas....
, scallop
Scallop

A scallop is a Marine bivalve mollusk of the Family Pectinidae. Scallops are a wiktionary:cosmopolitan family, found in all of the world's oceans....
s, 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, wheat germ, and hawthorne.

Higher levels of meat and seafood consumption are associated with an increased risk of gout
Gout

Gout is a crystal deposition disease hallmarked by elevated levels of uric acid in the Circulatory system. In this condition, crystals of monosodium urate or uric acid are deposited on the articular cartilage of joints, tendons and surrounding tissues....
, whereas a higher level of consumption of dairy products is associated with a decreased risk. Moderate intake of purine-rich vegetables or protein is not associated with an increased risk of gout
Gout

Gout is a crystal deposition disease hallmarked by elevated levels of uric acid in the Circulatory system. In this condition, crystals of monosodium urate or uric acid are deposited on the articular cartilage of joints, tendons and surrounding tissues....
.

Laboratory synthesis

In addition to in vivo
In vivo

In vivo means that which takes place inside an organism. In science, in vivo refers to experimentation done in or on the living tissue of a whole, living organism as opposed to a partial or dead one or a in vitro....
 synthesis of purines in purine metabolism
Purine metabolism

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

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.

The Traube purine synthesis (1900) is a classic reaction (named after Wilhelm Traube
Wilhelm Traube

Wilhelm Traube was a Germany chemist....
) between an amine
Amine

Amines are organic compounds and functional groups that contain a base nitrogen atom with a lone pair. Amines are derivative s of ammonia, wherein one or more hydrogen atoms are replaced by organic substituents such as alkyl and aryl groups....
 substutited pyrimidine
Pyrimidine

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring....
 and formic acid
Formic acid

Formic acid is the simplest carboxylic acid. Its formula is hydrogencarbonoxygenOH or CH2O2. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stingers....
 

See also

  • Simple aromatic ring
    Simple aromatic ring

    Simple aromatic rings, also known as simple arenes or simple aromatics, are aromatic organic compounds that consist only of a conjugated system planar ring system with delocalized_electron pi electron clouds....
    s
  • Pyrimidine
    Pyrimidine

    Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring....


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