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Pyrimidine

From Biocrawler, the free encyclopedia.

Pyrimidine
Chemical name	Pyrimidine
Chemical formula	C₄H₄N₂
Molecular mass	80.09 g/mol
Density	1.016 g/ml
Melting point	20 - 22 °C
Boiling point	123 - 124 °C
CAS number	289-95-2
SMILES	C1=NC=NC=C1

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

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


Thymine	Uracil	Cytosine

These hydrogen bonding modes are for classical Watson-Crick base pairing. Other hydrogen bonding modes 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.

Contents

1 Pyrimidine biosynthesis

1.1 Pyrimidine de novo biosynthesis
1.2 Pyrmidine catabolism

2 Suppliers/Manufacturers

3 See also

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Pyrimidine biosynthesis

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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.

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Pyrmidine catabolism

Pyrimidines are broken down completely to CO2. H2O and urea. Cytosine can be broken down to uracil which can be further broken down to N-carbaomyl-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.

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Suppliers/Manufacturers

Lancaster (http://www.lancastersynthesis.com/homecatsearch.htm) (now part of Alfa)
Fisher (https://www1.fishersci.com/index.jsp)
VWR (http://www.vwr.com/index.htm)
Alfa (http://www.alfa.com/alf/index.htm)
Aldrich (http://www.sigmaaldrich.com)
Aurora Fine Chemicals (http://www.aurora-feinchemie.com)