Navigation Links
Purine



Purine
Chemical namePurine
Chemical formulaC5H4N4
Molecular mass120.11 g/mol
Melting point214 C
CAS number120-73-0
SMILESC1(NC=N2)=C2C=NC=N1

Purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring.

The general term purines also refers to substituted purines and their tautomers. Two of the bases in nucleic acids, adenine and guanine, are purines. In DNA, these bases form hydrogen bonds with their complementary pyrimidines thymine and cytosine.

purine  pyrimidine
  A         T
  G         C

In RNA, the complement of A is uracil instead of thymine:

purine  pyrimidine
  A         U
  G         C
Adenine Guanine

These hydrogen bonding modes are for classical Watson-Crick base pairing. Other hydrogen bonding modes are seen in both DNA and RNA. Of significance, the additional 2'-hydroxyl group of the ribose moiety in RNA expands the configurations through which RNA can form hydrogen bonds.

Other notable purines are xanthine, hypoxanthine, theobromine, and caffeine.

Purines are biochemically significant as components of DNA and RNA, and are also found in a number of other important biomolecules, such as ATP, GTP, cyclic AMP, NADH, and coenzyme A.

Metabolism

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

Purines are biologically synthesized as nucleotides (bases attached to ribose). Both adenine and guanine are derived from the nucleotide inosine monophosphate, which is synthesized on a pre-existing ribose through a complex pathway using atoms from the amino acids glycine, glutamine, and aspartic acid, as well as formate ions transferred from the coenzyme tetrahydrofolate.

Purines from food (or from tissue turnover) are metabolized by several enzymes, including xanthine oxidase, into uric acid. High levels of uric acid can predispose to gout when the acid crystalizes in joints; this phenomenon only happens in humans and some animal species (e.g. dogs) that lack an intrinsic urease enzyme that can further degrade uric acid. The deficiency of another enzyme, adenosine deaminase, needed to break down adenine, is a cause of severe combined immunodeficiency.

Purines from turnover of nucleic acids (or from food) can also be salvaged and reused in new nucleotides. The enzyme adenine phosphoribosyltransferase salvages adenine, while hypoxanthine-guanine phosphoribosyltransferase (HPRT) salvages guanine and hypoxanthine. Genetic deficiency of HPRT causes Lesch-Nyhan syndrome.

History

Purine was named by the German chemist Emil Fischer in 1884. He synthesized it in 1898. Fischer showed that the Purines were part of a single chemical family.

See also


'"/>


(Date:3/20/2015)... 2015 Research and Markets ( http://www.researchandmarkets.com/research/rswjb4/hand_geometry ) ... Global Strategic Business Report" report to their offering. ... in US$ Thousands. The report provides separate comprehensive analytics for ... , Europe , Asia-Pacific ... of World. Annual estimates and forecasts are provided ...
(Date:3/19/2015)... , March 19, 2015  NXT-ID, Inc. (NASDAQ: ... company focused on the growing mobile commerce market, announces its ... a news clip that aired this week on ... . In a segment "The Next Great Thing", ... ,a new way to pay, and ,a really big breakthrough ...
(Date:3/17/2015)... , March 17, 2015 Emotient, the ... software, today announced general availability of Emotient ... for the analysis of facial expressions. The system ... media content, products and services. It delivers audience ... and sentiment - as derived from facial evidence ...
Breaking Biology News(10 mins):Hand Geometry - Global Strategic Business Report 2015: An Essential Security Component for both Government & Enterprise Sector 2Hand Geometry - Global Strategic Business Report 2015: An Essential Security Component for both Government & Enterprise Sector 3Hand Geometry - Global Strategic Business Report 2015: An Essential Security Component for both Government & Enterprise Sector 4NXT-ID's Wocket Smart Wallet Featured on Fox News Segment, "The Next Great Thing" 2NXT-ID's Wocket Smart Wallet Featured on Fox News Segment, "The Next Great Thing" 3New Emotient Web Service Measures Audience Response Using On-Demand Facial Expression Analysis 2New Emotient Web Service Measures Audience Response Using On-Demand Facial Expression Analysis 3New Emotient Web Service Measures Audience Response Using On-Demand Facial Expression Analysis 4
... Tenn., June 26, 2008 Dozens of instruments to ... sites around the nation will provide valuable information related ... and other areas of interest. Walker Branch Watershed ... will be part of the National Ecological Observatory Network, ...
... research groups around Australia, the report includes chapters on ... on steps that can be taken to adjust to ... the Farm Writers Association of NSW in Sydney today, ... said it was time for agriculture to start focussing ...
... Mexico about 10,000 years ago and is now one of ... It is a member of the grass family, which also ... sorghum, and sugar cane. As early agriculturalists selected ... for transforming a wild grass into a food plant. ...
Cached Biology News:Oak Ridge pegged for national ecological network 2Ancient Mexican maize varieties 2Ancient Mexican maize varieties 3
Other biology definitionOther Tags