- One of the two classes of bases in DNA and RNA. The pyrimidine bases are thymine (T) and cytosine (C) in DNA and thymine (T) and uracil (U) in RNA.
* * *1,3-Diazine; a heterocyclic substance, the formal parent of several “bases” present in nucleic acid s (uracil, thymine, cytosine) as well as of the barbiturates.- p. 5′-nucleotidase an enzyme that catalyzes the hydrolysis of a p.-nucleoside 5′-monophosphate to produce orthophosphate and the p. nucleoside; a deficiency of this enzyme results in accumulation of p. nucleotides leading to hemolytic anemia.- p. transferase SYN: thiamin pyridinylase.
* * *py·rim·i·dine pī-'rim-ə-.dēn, pə- n1) a weakly basic organic compound C4H2N2 of penetrating odor that is composed of a single six-membered ring having four carbon atoms with nitrogen atoms in positions one and three2) a derivative of pyrimidine having its characteristic ring structure esp a base (as cytosine, thymine, or uracil) that is a constituent of DNA or RNA
* * *n.a nitrogen-containing compound with a ring molecular structure. The commonest pyrimidines are cytosine, thymine, and uracil, which form the nucleotide of nucleic acids.
* * *py·rim·i·dine (pə-rimґĭ-dēn) an organic compound, a metadiazine, C4H4N2, which is the fundamental form of the pyrimidine bases. These are mostly oxy or amino derivatives, for example, 2,4-dioxypyrimidine is uracil, 2-oxy-4-aminopyrimidine is cytosine, and 2,4-dioxy-5-methylpyrimidine is thymine, all of which are constituents of nucleic acid. See illustration of purine and pyrimidine bases, under base.
Medical dictionary. 2011.