Pyrimidine bases

Pyrimidine base - six-membered heterocyclic derivatives of pyrimidine (1,3-diazine, or meridiasin;the formula C4H4N2)
                             
Natural pyrimidine derivatives called bases, although in reality some basic properties do not possess. Pyrimidine bases are widely distributed in nature and occur in all cells of animals and plants, microorganisms and viruses, mainly in the composition of nucleic acids, nucleotides, some ferments, vitamins and other products Among hydrolytic decomposition of nucleic acids (see), nucleotides (see) and nucleoside discovered P. O.: uracil (2,6-deoxidized), thymine (5-methyl-uracil) and cytosine (2-hydroxy-6-aminopyrimidine)
                    
Pyrimidine ring is part of a more complex condensed cyclic systems (for example, purines, italicizing and others).
Almost all natural P. O. contain axagroup, allowing able to Ketorolac (victim-lactam) tautomerism, for example,
                  
Part of nucleotides and nucleoside P. O. enter into ketone form.
All pyrimidine bases - a colorless crystalline substance, usually poorly soluble in water and better in alkalis. Depending on the number and nature of substituents they have weak key (2-aminopyrimidine), amphoteric (cytosine) or acid (uracil, orotic acid) properties. With the growing number of axagroup acidity is noticeable.
For all P. O. characterized by the ability to absorb UV rays that is used for identification and quantification (usually after chromatographic separation).
The biological role of pyrimidine bases due to their involvement in the construction of nucleic acids, many coenzymes and nucleotides. Their biosynthesis is from aspartic acid, which, interacting with carbamylphosphate, forms weidendamm, dihydroorotate and then orotova acid. Last, interacting with phosphoribosylpyrophosphate, enters urocidin monophosphate and then the uridine-5'-monophosphate. Further aminating of uridine-5'-monophosphate formed citizen-5'-monophosphate. When restoring, uridine-5'-monophosphate or deamination of deoxycytidine-5'-monophosphate formed deoxyuridine-5'-monophosphate. When methylation last (as coenzyme is tetragidrofolieva acid) is formed deoxythymidine-5'-monophosphate.
The end products of disintegration P. O. in animals can be urea, water and carbon dioxide. As intermediates formed b-amino - beta-alanine (from uracil and cytosine) or β aminoazotoluene (thymine).