Difference between revisions of "Guanine" - New World Encyclopedia

Revision as of 19:29, 30 December 2006

Guanine

General
Systematic name	2-amino-1H-purin-6(9H)-one
Other names	2-amino-6-oxo-purine, 2-aminohypoxanthine, Guanine
Molecular formula	C₅H₅N₅O
SMILES	NC(NC1=O)=NC2=C1N=CN2
Molar mass	151.1261 g/mol
Appearance	White amorphous solid.
CAS number	[73-40-5] [1]
Properties
Density and phase	? g/cm³, solid.
Solubility in water	Insoluable.
Melting point	360°C (633.15 K) deco.
Boiling point	Sublimes.
Structure
Crystal structure	?
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	Irritant.
NFPA 704	1 1 0
Flash point	Non-flammable.
R/S statement	R: R36, R37, R38. S: R24/25, R26, R36.
RTECS number	MF8260000
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	?
Other cations	?
Related compounds	Cytosine, Adenine, Thymine, Uracil
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa)

Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA; the others being adenine, cytosine, thymine, and uracil. Guanine and adenine are purine derviatives, and cytosine, thymine, and uracil are pyrimidine derivaties.

With the formula C₅H₅N₅O, guanine consists of a fused pyrimidine-imidazole ring system with conjugated double bonds. Being unsaturated, the bicyclic molecule is planar. The guanine nucleoside is called guanosine.

In DNA, guanine and adenine form hydrogen bonds with their complementary pyrimidine derivatives, cytosine and thymine. In RNA, the complement of adenine is uracil instead of thymine. Thus, guanine, along with adenine and cytosine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA and uracil only in RNA.

Basic properties

Guanine has two tautomeric forms, the keto form and enol form. It binds to cytosine through three hydrogen bonds. In cytosine, the amino group acts as the hydrogen donor and the C-2 carbonyl and the N-3 amine as the hydrogen-bond acceptors. Guanine has a group at C-6 that acts as the hydrogen acceptor, while the group at N-1 and the amino group at C-2 acts as the hydrogen donors.

Guanine can be hydrolyzed with strong acid at 180°C to glycine, ammonia, carbon dioxide, and carbon monoxide. Guanine oxidizes more readily than adenine, the other purine-derivative base in DNA and RNA. Its high melting point of 350°C reflects the strong intermolecular hydrogen bonding between the oxo and amino groups in the molecules in the crystal. Because of this intermolecular bonding, guanine is relatively insoluble in water, although it is soluble in dilute acids and bases.

History

The first isolation of guanine was reported in 1844 from sea bird excreta, known as guano, which was used as a source of fertilizer. About fifty years later, the structure was determined by Fischer and it was shown that uric acid can be converted to guanine. The first complete synthesis was done by Traube and remains among the best large-scale preparations.

Syntheses

Trace amounts of guanine form by the polymerization of ammonium cyanide (NH₄CN). Two experiments conducted by Levy et al., showed that heating 10 M NH₄CN at 80°C for 24 hours gave a yield of 0.0007% while using 0.1 M NH₄CN frozen at -20°C for 25 years gave a 0.0035% yield. These results indicate guanine could arise in frozen regions of the primitive earth. In 1984, Yuasa reported a 0.00017% yield of guanine after the electrical discharge of NH₃, CH₄, C₂H₆, and 50 mL of water, followed by a subsequent acid hydrolysis. However, it is unknown if the presence of guanine was not simply resulted from a contaminant of the reaction.

5NH₃ + CH₄ + 2C₂H₆ + H₂O → C₅H₈N₅O (guanine) + (25/2)H₂

A Fischer-Tropsch synthesis can also be used to form guanine, along with adenine, uracil and thymine. Heating an equimolar gas mixture of CO, H₂, and NH₃ to 700 °C for 0.24 to 0.4 hours, followed by quick cooling and then sustainted reheating to 100-200°C for 16-44 hours with an alumina catalyst yielded guanine and uracil:

5CO + (1/2)H₂ + 5NH₃ → C₅H₈N₅O (guanine) + 4H₂O

Traube's synthesis involves heating 2,4,5-triamino-1,6-dihydro-6-oxypyrimidine (as the sulphate) with formic acid for several hours.

Other uses

In 1656 in Paris, François Jaquin (a rosary maker) extracted from scales of some fishes the so called pearl essence, crystalline guanine forming G-quadruplexes: in cosmetic industry, crystalline guanine is used as an additive to various products (e.g., shampoos), where it provides the pearly iridescent effect. It is also used in metallic paints and simulated pearls and plastics. It provides shimmering lustre to eye shadow and nail polish. Guanine crystals are rhombic platelets composed of multiple, transparent layers but they have a high index of refraction that partially reflects and transmits light from layer to layer thus producing a pearly luster. It can be applied by spray, painting or dipping. It may irritate eyes. Its alternatives are mica, synthetic pearl, and aluminium and bronze particles.

References
ISBN links support NWE through referral fees

1. Miyakawa, S., Murasawa, K., Kobayashi, K., Sawaoka, AB. "Abiotic synthesis of guanine with high-temperature plasma." Orig Life Evol Biosph. 30(6): 557-66, Dec. 2000. <br\> 2. Horton, H.R., Moran, L.A., Ochs, R.S., Rawn, J.D., Scrimgeour, K.G. "Principles of Biochemistry." Prentice Hall (New Jersey). 3rd Edition, 2002. <br\> 3. Lister, J.H. "Part II Purines." The Chemistry of Heterocyclic Compounds. Wiley-Interscience (New York). 1971.

External links

Nucleic acids edit
Nucleobases: Adenine - Thymine - Uracil - Guanine - Cytosine - Purine - Pyrimidine
Nucleosides: Adenosine - Uridine - Guanosine - Cytidine - Deoxyadenosine - Thymidine - Deoxyguanosine - Deoxycytidine
Nucleotides: AMP - UMP - GMP - CMP - ADP - UDP - GDP - CDP - ATP - UTP - GTP - CTP - cAMP - cGMP
Deoxynucleotides: dAMP - dTMP - dUMP - dGMP - dCMP - dADP - dTDP - dUDP - dGDP - dCDP - dATP - dTTP - dUTP - dGTP - dCTP
Nucleic acids: DNA - RNA - LNA - PNA - mRNA - ncRNA - miRNA - rRNA - siRNA - tRNA - mtDNA - Oligonucleotide

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

Guanine ^history

The history of this article since it was imported to New World Encyclopedia:

History of "Guanine"

Note: Some restrictions may apply to use of individual images which are separately licensed.

@@ Line 30: / Line 30: @@
 ! {{chembox header}} | Properties
 |-
-| [[Density]]* and [[Phase (matter)|phase]]
+| [[Density]]* and [[Phase (matter)|phase]]*
 | ? g/cm<sup>3</sup>, solid.
 |-
-| [[Solubility]] in [[Water (molecule)|water]]*
+| [[Solubility]]* in [[Water (molecule)|water]]*
 | Insoluable.
 |-
@@ Line 98: / Line 98: @@
 |-
 |}
-'''Guanine''' is one of the five main [[nucleotide#Chemical structure and nomenclature|nucleobase]]s found in the [[nucleic acid]]s [[DNA]] and [[RNA]]; the others being [[adenine]], [[cytosine]], [[thymine]], and [[uracil]].  With the formula C<sub>5</sub>H<sub>5</sub>N<sub>5</sub>O, guanine is a [[purine]] derivative, consisting of a fused [[pyrimidine]]-imidazole ring system with conjugated double bonds. Being unsaturated, the bicyclic molecule is planar.  The guanine [[nucleotide#Chemical structure and nomenclature|nucleoside]] is called guanosine.
+'''Guanine''' is one of the five main [[nucleotide#Chemical structure and nomenclature|nucleobase]]s found in the [[nucleic acid]]s [[DNA]] and [[RNA]]; the others being [[adenine]], [[cytosine]], [[thymine]], and [[uracil]]. Guanine and adenine are [[purine]] derviatives, and cytosine, thymine, and uracil are pyrimidine derivaties.
-In DNA, adenine and guanine, which are purine derivatives, form hydrogen bonds with their complementary pyrimidine derivatives, thymine and cytosine. In RNA, the complement of adenine is uracil instead of thymine.
+With the formula C<sub>5</sub>H<sub>5</sub>N<sub>5</sub>O, guanine consists of a fused [[pyrimidine]]-imidazole ring system with conjugated double bonds. Being unsaturated, the bicyclic molecule is planar.  The guanine [[nucleotide#Chemical structure and nomenclature|nucleoside]] is called guanosine.
-==Basic principles==
+In DNA, guanine and adenine form hydrogen bonds with their complementary pyrimidine derivatives, cytosine and thymine. In RNA, the complement of adenine is uracil instead of thymine. Thus, guanine, along with adenine and cytosine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA and uracil only in RNA.
-Guanine, along with adenine and cytosine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA and uracil only in RNA.  Guanine has two tautomeric forms, the [[keto-enol tautomerism|keto form and enol form]].
-It binds to cytosine through three [[hydrogen bond]]s.  In cytosine, the amino group acts as the hydrogen donor and the C-2 carbonyl and the N-3 amine as the hydrogen-bond  acceptors.  Guanine has a group at C-6 that acts as the hydrogen acceptor, while the group at N-1 and the amino group at C-2 acts as the hydrogen donors.
+==Basic properties==
+Guanine has two tautomeric forms, the keto form and enol form. It binds to cytosine through three hydrogen bonds. In cytosine, the amino group acts as the hydrogen donor and the C-2 carbonyl and the N-3 amine as the hydrogen-bond  acceptors. Guanine has a group at C-6 that acts as the hydrogen acceptor, while the group at N-1 and the amino group at C-2 acts as the hydrogen donors.
 {| align="center"
 |-
@@ Line 111: / Line 112: @@
 |}
-==Isolation, background, & some chemistry==
+Guanine can be hydrolyzed with strong acid at 180°C to glycine, ammonia, [[carbon dioxide]], and [[carbon monoxide]]. Guanine oxidizes more readily than [[adenine]], the other purine-derivative base in DNA and RNA. Its high melting point of 350°C reflects the strong intermolecular hydrogen bonding between the oxo and amino groups in the molecules in the crystal. Because of this intermolecular bonding, guanine is relatively insoluble in water, although it is soluble in dilute acids and bases.
-The first isolation of guanine was reported in 1844 from the excreta of sea birds, known as guano, which was used as a source of fertilizer.  About fifty years Fischer determined the structure and also showed that uric acid can be converted to guanine.  The first complete synthesis was done by Traube and remains among the best large-scale preparations.
-Guanine can be hydrolyzed with strong acid to glycine, ammonia, carbon dioxide, and carbon monoxide at 180°C.  Guanine oxidizes more readily than adenine, the other purine-derivative base in DNA and RNA.  Its  high melting point of 350°C reflects the intermolecular hydrogen bonding between the oxo and amino groups in the molecules in the crystal.  Because of this intermolecular bonding, guanine is relatively insoluble in water, although it is soluble in dilute acids and bases.
+==History==
+The first isolation of guanine was reported in 1844 from sea bird excreta, known as guano, which was used as a source of fertilizer. About fifty years later, the structure was determined by Fischer and it was shown that uric acid can be converted to guanine. The first complete synthesis was done by Traube and remains among the best large-scale preparations.
 ==Syntheses==