-
Hermann Emil Fischer
Hermann Emil Fischer, Emil Fischer (9 October 1852, Euskirchen, Rhine Province – 15 July 1919) was a German chemist and recipient of the Nobel Prize for Chemistry in 1902. He is known for discovering the Fischer esterification.
http://wn.com/Hermann_Emil_Fischer -
Wilhelm Traube
Wilhelm Traube (10 January 1866 – 28 September 1942) was a German chemist.
http://wn.com/Wilhelm_Traube
-
Germany (), officially the Federal Republic of Germany (, ), is a country in Western 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. The territory of Germany covers 357.021 km2 and is influenced by a temperate seasonal climate. With 81.8 million inhabitants, it is the most populous member state of the European Union, and home to the third-largest number of international migrants worldwide.
http://wn.com/Germany -
The National Aeronautics and Space Administration (NASA, ) is an Executive Branch agency of the United States government, responsible for the nation's civilian space program and aeronautics and aerospace research. Since February 2006, NASA's self-described mission statement is to "pioneer the future in space exploration, scientific discovery and aeronautics research."
http://wn.com/NASA
- adenine
- adenosine receptor
- amine
- anchovies
- aromatic
- caffeine
- chemist
- coenzyme A
- cyclic AMP
- cytosine
- deoxyribonucleotide
- DNA
- Earth
- formamide
- formic acid
- Germany
- gout
- guanine
- Hermann Emil Fischer
- hydrogen bond
- Hydrogen cyanide
- hydrogen iodide
- hypoxanthine
- imidazole
- in vivo
- isoguanine
- mackerel
- meat extract
- metabolic pathway
- Metabolism
- meteorites
- NADH
- NASA
- neurotransmitters
- nitrogenous bases
- nucleic acid
- nucleoside
- nucleotide bases
- organic compound
- organic molecules
- organic synthesis
- outer space
- Phosphonium salt
- PNAS
- purine metabolism
- purinergic receptors
- pyrimidine
- ribonucleotide
- ribose
- RNA
- sardine
- scallop
- Simple aromatic ring
- sweetbread
- tautomer
- theobromine
- thymine
- uracil
- uric acid
- Wilhelm Traube
- xanthine

- Order: Reorder
- Duration: 2:15
- Published: 11 Dec 2009
- Uploaded: 07 Dec 2011
- Author: TryptophanLNS

- Order: Reorder
- Duration: 3:40
- Published: 01 Mar 2011
- Uploaded: 01 Mar 2011
- Author: fruges7528


- Order: Reorder
- Duration: 2:20
- Published: 21 Dec 2010
- Uploaded: 03 Dec 2011
- Author: ChrisLeggettMusic

- Order: Reorder
- Duration: 1:16
- Published: 02 Jan 2011
- Uploaded: 27 Sep 2011
- Author: ChrisLeggettMusic

- Order: Reorder
- Duration: 0:52
- Published: 16 Sep 2011
- Uploaded: 16 Sep 2011
- Author: DTO214daily

- Order: Reorder
- Duration: 1:46
- Published: 17 Feb 2011
- Uploaded: 19 Feb 2011
- Author: fruges7528

- Order: Reorder
- Duration: 3:08
- Published: 17 May 2009
- Uploaded: 29 Mar 2010
- Author: potatorato

- Order: Reorder
- Duration: 0:54
- Published: 12 Oct 2011
- Uploaded: 12 Oct 2011
- Author: DTO214daily

- Order: Reorder
- Duration: 0:47
- Published: 12 Oct 2011
- Uploaded: 12 Oct 2011
- Author: DTO214daily

- Order: Reorder
- Duration: 9:52
- Published: 02 Aug 2010
- Uploaded: 31 Oct 2011
- Author: kevingianni

- Order: Reorder
- Duration: 0:49
- Published: 16 Sep 2011
- Uploaded: 16 Sep 2011
- Author: DTO214daily

- Order: Reorder
- Duration: 1:23
- Published: 20 Oct 2011
- Uploaded: 20 Oct 2011
- Author: DTO214daily

- Order: Reorder
- Duration: 17:28
- Published: 15 Oct 2011
- Uploaded: 13 Nov 2011
- Author: EliteBoardReview

- Order: Reorder
- Duration: 14:42
- Published: 01 Oct 2011
- Uploaded: 16 Nov 2011
- Author: EliteBoardReview

- Order: Reorder
- Duration: 1:13
- Published: 20 Oct 2011
- Uploaded: 20 Oct 2011
- Author: DTO214daily

- Order: Reorder
- Duration: 5:07
- Published: 24 Oct 2007
- Uploaded: 25 Apr 2011
- Author: WaynoDraino


- Order: Reorder
- Duration: 0:20
- Published: 10 Jul 2009
- Uploaded: 16 Oct 2011
- Author: wolframmathematica

- Order: Reorder
- Duration: 0:56
- Published: 05 Sep 2011
- Uploaded: 05 Sep 2011
- Author: DTO214daily

- Order: Reorder
- Duration: 0:47
- Published: 05 Sep 2011
- Uploaded: 05 Sep 2011
- Author: DTO214daily


- Order: Reorder
- Duration: 1:08
- Published: 19 Nov 2010
- Uploaded: 19 Nov 2010
- Author: mattstersa









size: 2.5Kb
-
Iran files complaint over purported US drone Al Jazeera
-
Euro crisis summit: The night Europe changed BBC News
-
Before Voting, If Only Death Had Been Before Their Own Eyes WorldNews.com
-
Israeli airstrikes hit Gaza civilians Sydney Morning Herald
-
Italian police arrest alleged Mafia boss hiding in bunker CNN
- abiogenesis
- adenine
- adenosine receptor
- amine
- anchovies
- aromatic
- caffeine
- chemist
- coenzyme A
- cyclic AMP
- cytosine
- deoxyribonucleotide
- DNA
- Earth
- formamide
- formic acid
- Germany
- gout
- guanine
- Hermann Emil Fischer
- hydrogen bond
- Hydrogen cyanide
- hydrogen iodide
- hypoxanthine
- imidazole
- in vivo
- isoguanine
- mackerel
- meat extract
- metabolic pathway
- Metabolism
- meteorites
- NADH
- NASA
- neurotransmitters
- nitrogenous bases
- nucleic acid
- nucleoside
- nucleotide bases
- organic compound
- organic molecules
- organic synthesis
- outer space
- Phosphonium salt
- PNAS
- purine metabolism
- purinergic receptors
- pyrimidine
- ribonucleotide
- ribose
- RNA
- sardine
- scallop
- Simple aromatic ring
- sweetbread
- tautomer
- theobromine
- thymine
- uracil
- uric acid
size: 1.0Kb
size: 11.4Kb
size: 3.0Kb
size: 2.0Kb
size: 5.6Kb
size: 0.8Kb
A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines, including substituted purines and their tautomers, 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 deoxyribonucleotides and two of the four ribonucleotides, the respective building blocks of DNA and RNA, are purines.
Notable purines
The quantity of naturally occurring purines produced on earth is huge. Two of the four 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, respectively. This is called complementary base pairing. In RNA, the complement of adenine is uracil 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. 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 to give 2,6-diiodopurine (11). The 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).
Sources
Purines are found in high concentration in meat and meat products, especially internal organs such as liver and kidney. Plant based diets are generally low in purines. Examples of high-purine sources include: sweetbreads, anchovies, sardines, liver, beef kidneys, brains, meat extracts (e.g., Oxo, Bovril), herring, mackerel, scallops, game meats, beer (from the yeast) and gravy.A moderate amount of purine is also contained in beef, pork, poultry, other fish and seafood, asparagus, cauliflower, spinach, mushrooms, green peas, lentils, dried peas, beans, oatmeal, wheat bran, wheat germ, and hawthorn.
Higher levels of meat and seafood consumption are associated with an increased risk of gout, 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.
In August 2011, a report, based on NASA studies with meteorites found on Earth, was published suggesting purine and related organic molecules (including the DNA and RNA components, adenine and guanine) may have been formed extraterrestrially in outer space.
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 °C for 28 hours.
This remarkable reaction and others like it have been discussed in the context of the origin of life.
Procedure: Formamide (45 grams) was heated in an open vessel with a condenser for 28 hours in an oil bath at 170-190 °C. After removing excess formamide (32.1 grams) 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 grams (71% yield from formamide consumed). Crystallization from acetone afforded purine as colorless crystals; melting point 218 °C.
Oro, Orgel and co-workers have shown that four molecules of HCN tetramerize to form diaminomaleodinitrile (12), which can be converted into almost all natural-occurring purines.
The Traube purine synthesis (1900) is a classic reaction (named after Wilhelm Traube) between an amine-substituted pyrimidine and formic acid.
See also
References
External links
This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.