Pyrimidine

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{{{name|Pyrimidine}}}
Chemical name	Pyrimidine}}}
Chemical formula	C4H4N2}}}
Molecular mass	80.09}}} g/mol
CAS number	289-95-2}}}]
Density	1.016}}} g/cm3
Melting point	20–22}}} °C
Boiling point	123–124}}} °C
SMILES	C1=NC=NC=C1}}}
Disclaimer and references

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. It is isomeric with two other forms of diazine.

Image:Pyrimidine chemical structure.png

Three nucleobases found in nucleic acids, namely cytosine, thymine, and uracil, are pyrimidine derivatives. In DNA and RNA, these bases form hydrogen bonds with their complementary purines.

purine  pyrimidine
   A         T
   G         C

In RNA, the complement of A is U instead of T:

purine  pyrimidine
   A         U
   G         C

These hydrogen bonding modes are for classical Watson-Crick base pairing. Other hydrogen bonding modes ("wobble pairings") are available in both DNA and RNA, although the additional 2'-hydroxyl group of RNA expands the configurations through which RNA can form hydrogen bonds.

Image:Thymine chemical structure.png	Image:Uracil chemical structure.png	Image:Cytosine chemical structure.png
Thymine	Uracil	Cytosine

Contents 1 Pyrimidine biosynthesis 1.1 Pyrimidine de novo biosynthesis 1.2 Pyrmidine catabolism 2 Suppliers/Manufacturers 3 See also

Pyrimidine biosynthesis

Pyrimidine de novo biosynthesis

Unlike purines, pyrimidines are assembled before being attached to 5-phosphoribosyl-1-pyrophosphate (PRPP). The first step begins with formation of carbamoyl phosphate by carbamoyl phosphate synthetase II. The second major step is the creation carbamoyl aspartic acid formed by aspartic transcarbamolyase. Once orotic acid is eventually formed from carbamoyl aspartic acid, it is combined with PRPP to form uridine-3'-phosphate (UMP). UMP is then phosphorylated twice to form ribose-PPP-Uridine-5'-triphosphate (UTP).

Cytidino-5'-triphosphate (CTP) is formed from UTP utilizing glutamine.

Pyrmidine catabolism

Pyrimidines are ultimately catabolized (degraded) to CO₂, H₂O, and urea. Cytosine can be broken down to uracil which can be further broken down to N-carbamoyl-β-alanine. Thymine is broken down into β-aminoisobutyrate which can be further broken down into intermediates eventually leading into the citric acid cycle. β-aminoisobutyrate acts as a rough indicator for rate of DNA turnover.

Suppliers/Manufacturers

• Lancaster (now part of Alfa)
• Fisher
• VWR
• Alfa
• Aldrich
• Aurora Fine Chemicals

See also

• Pyrazine, an analog with the nitrogen atoms in positions 1 and 4.
• Pyridazine, an analog with the nitrogen atoms in positions 1 and 2.
• Simple aromatic rings

Template:Nucleic acids

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